need help with error

why it say" reactor:306: attempt to index ? (a nil value)"?
how can i fix that?
here is the code

os.loadAPI("button")
p = peripheral.find("tile_blockcapacitorbank_name")
m = peripheral.find("monitor")
r = peripheral.find("BigReactors-Reactor")
t = peripheral.find("BigReactors-Turbine")
local steamReactor = r.isActivelyCooled()
local menuType = "Reactor"
local numCapacitors = 90
local turnOnAt = 50
local turnOffAt = 90
local targetSpeed = 1840
local energy = 0
local energyStored = 0
local energyMax = 0
local energyStoredPercent = 0
local timerCode
local mode = "Automatic"
local RFProduction = 0
local fuelUse = 0
local coreTemp = 0
local reactorOnline = false
local rodLevel = 0
local turbineOnline = false
local turbineRotorSpeed = 0
local turbineRFGen = 0
local turbineFluidRate = 0
local turbineInductor = false
local OptFuelRodLevel = 0
function autoMenu()
   m.setTextScale(1)
   button.clearTable()
   button.setTable("Automatic", autoMode, "", 3, 13, 6, 6)
   button.setTable("Manual", manualMode, "", 15, 25, 6, 6)
  
   if steamReactor then
	  button.setTable("Reactor", reactorMenu, "", 5, 18, 19, 19)
	  button.setTable("Turbine", turbineMenu, "", 22, 35, 19, 19)
   end
   button.screen()
   checkMode()
   menuMode()
end
function manualMenu()
   m.setTextScale(1)
   button.clearTable()
   button.setTable("Automatic", autoMode, "", 3, 13, 6, 6)
   button.setTable("Manual", manualMode, "", 15, 25, 6, 6)
   button.setTable("Online", online, "", 3, 13, 8, 8)
   button.setTable("Offline", offline, "", 15, 25, 8, 8)
   button.setTable("0", setRods, 0, 11,14, 10, 10)
   button.setTable("10", setRods, 10, 5,8, 12, 12)
   button.setTable("20", setRods, 20, 11,14, 12, 12)
   button.setTable("30", setRods, 30, 17,20, 12, 12)
   button.setTable("40", setRods, 40, 5,8, 14, 14)
   button.setTable("50", setRods, 50, 11,14, 14, 14)
   button.setTable("60", setRods, 60, 17,20, 14, 14)
   button.setTable("70", setRods, 70, 5,8, 16, 16)
   button.setTable("80", setRods, 80, 11,14, 16, 16)
   button.setTable("90", setRods, 90, 17,20, 16, 16)
   button.setTable("+", rodPlus, "", 23, 25, 12, 12)
   button.setTable("-", rodMinus, "", 23, 25, 16, 16)
   if steamReactor then
	  button.setTable("Reactor", reactorMenu, "", 5, 18, 19, 19)
	  button.setTable("Turbine", turbineMenu, "", 22, 35, 19, 19)
  
   end
   button.screen()
   checkMode()
   reactorOnOff()
   menuMode()
end
function turbineAutoMenu()
   m.setTextScale(1)
   button.clearTable()
   button.setTable("Automatic", autoMode, "", 3, 13, 6, 6)
   button.setTable("Manual", manualMode, "", 15, 25, 6, 6)
   button.setTable("Reactor", reactorMenu, "", 5, 18, 19, 19)
   button.setTable("Turbine", turbineMenu, "", 22, 35, 19, 19)
   button.screen()
   checkMode()
   menuMode()
end
function turbineManualMenu()
   m.setTextScale(1)
   button.clearTable()
   button.setTable("Automatic", autoMode, "", 3, 13, 6, 6)
   button.setTable("Manual", manualMode, "", 15, 25, 6, 6)
   button.setTable("Reactor", reactorMenu, "", 5, 18, 19, 19)
   button.setTable("Turbine", turbineMenu, "", 22, 35, 19, 19)
   button.setTable("Online", setTurbineOnline, "", 3, 13, 8, 8)
   button.setTable("Offline", setTurbineOffline, "", 15, 25, 8, 8)
   button.setTable("Coils On", coilsOn, "", 3, 13, 10, 10)
   button.setTable("Coils Off", coilsOff, "", 15, 25, 10, 10)
   button.screen()
   checkMode()
   turbineOnOff()
   coilsOnOff()
   menuMode()
end
function reactorMenu()
   menuType = "Reactor"
   displayScreen()
end
function turbineMenu()
   menuType = "Turbine"
   displayScreen()
end
function online()
   r.setActive(true)
   --button.flash("Online")
end
function offline()
   r.setActive(false)
   --button.flash("Offline")
end
function setTurbineOnline()
   t.setActive(true)
   --button.flash("Online")
end
function setTurbineOffline()
   t.setActive(false)
   --button.flash("Offline")
end
function reactorOnOff()
   button.setButton("Online", r.getActive())
   button.setButton("Offline", not r.getActive())
end
function turbineOnOff()
   button.setButton("Online", t.getActive())
   button.setButton("Offline", not t.getActive())
end
function coilsOnOff()
   button.setButton("Coils On", t.getInductorEngaged())
   button.setButton("Coils Off", not t.getInductorEngaged())
end
function coilsOn()
   t.setInductorEngaged(true)
end
function coilsOff()
   t.setInductorEngaged(false)
end
function menuMode()
   if steamReactor then
   if menuType == "Reactor" then
	 button.setButton("Reactor", true)
	 button.setButton("Turbine", false)
   else
	 button.setButton("Reactor", false)
	 button.setButton("Turbine", true)
   end
   end
end
function setRods(setLevel)
   print("Setting Rod Level: "..setLevel)
   button.flash(tostring(setLevel))
   r.setAllControlRodLevels(setLevel)
   fuelRodLevel()
end
function rodPlus()
   button.flash("+")
   r.setAllControlRodLevels(rodLevel+1)
   fuelRodLevel()
end
function rodMinus()
   button.flash("-")
   r.setAllControlRodLevels(rodLevel-1)
   fuelRodLevel()
end
function checkMode()
   button.toggleButton(mode)
end
  
function manualMode()
   mode = "Manual"
   manualMenu()
end
function autoMode()
   mode = "Automatic"
   displayScreen()
end
function comma_value(amount)
   local formatted = amount
   local swap = false
   if formatted < 0 then
	  formatted = formatted*-1
	  swap = true
   end
   while true do
	  formatted, k = string.gsub(formatted, "^(%d+)(%d%d%d)", '%1,%2')
	  if k == 0 then
		 break
	  end
   end
   if swap then
	 formatted = "-"..formatted
   end
   return formatted
end
function displayEn()
   m.clear()
   m.setCursorPos(1,1)
   --print("Energy Use: "..energy)
   m.write("Energy Use: ")
   if energy < 0 then
	  m.setTextColor(colors.red)
   else
	  m.setTextColor(colors.green)
   end
   m.write(comma_value(math.floor(energy)).. "RF/t")
   m.setTextColor(colors.white)
   m.setCursorPos(1,2)
   m.write("Energy Stored: "..energyStoredPercent.."%")
   if menuType == "Reactor" then
	  m.setCursorPos(1,3)
	  m.write("Reactor is: ")
	  if reactorOnline then
	m.setTextColor(colors.green)
	m.write("Online")
	  else
	   m.setTextColor(colors.red)
	m.write("Offline")
	  end
	  m.setTextColor(colors.white)
	  m.setCursorPos(22,1)
	  if steamReactor then
		 m.write("Steam: ")
	  m.setTextColor(colors.green)
		 m.write(comma_value(math.floor(RFProduction)).."MB/t")
	  else
		 m.write("RF Gen: ")
	  m.setTextColor(colors.green)
		 m.write(comma_value(math.floor(RFProduction)).."RF/t")
	  end
	  m.setTextColor(colors.white)
	  m.setCursorPos(22,2)
	  m.write("Core Temp: "..math.floor(coreTemp).."c")
	  m.setCursorPos(22,3)
	  m.write("Fuel Use: "..fuelUse.."MB/t")
  else
	  m.setCursorPos(1,3)
	  m.write("Turbine is: ")
	  if turbineOnline then
	m.setTextColor(colors.green)
	m.write("Online")
	  else
	   m.setTextColor(colors.red)
	m.write("Offline")
	  end
	  m.setCursorPos(1,4)
	  m.setTextColor(colors.white)
	  m.write("Reactor is: ")
	  if reactorOnline then
		 m.setTextColor(colors.green)
		 m.write("Online")
	  else
		 m.setTextColor(colors.red)
		 m.write("Offline")
	  end
	  m.setTextColor(colors.white)
   m.setCursorPos(22,1)
   m.write("RFGen: ")
   m.setTextColor(colors.green)
	  m.write(comma_value(math.floor(turbineRFGen)).."RF/t")
   m.setTextColor(colors.white)
   m.setCursorPos(22,2)
	  m.write("Rotor: "..comma_value(math.floor(turbineRotorSpeed)).." RPM")
   m.setCursorPos(22,3)
	  m.write("Steam: "..comma_value(turbineFluidRate).."MB/t")
  end

end
function checkEn()
   local tempEnergy = 0
   energyStored = p.getEnergyStored()
   energyMax = p.getMaxEnergyStored()
   energyStoredPercent = math.floor((energyStored/energyMax)*100)
   RFProduction = r.getEnergyProducedLastTick()
   fuelUse = r.getFuelConsumedLastTick()
   fuelUse = math.floor(fuelUse*100)
   fuelUse = fuelUse/100
   coreTemp = r.getFuelTemperature()
   reactorOnline = r.getActive()
   tempEnergy = p.getEnergyStored()
   sleep(0.1)
   energy = (p.getEnergyStored()-tempEnergy)/2
   energy = energy*numCapacitors
   if steamReactor then
	 turbineOnline = t.getActive()
	 turbineRotorSpeed = t.getRotorSpeed()
	 turbineRFGen = t.getEnergyProducedLastTick()
	 turbineFluidRate = t.getFluidFlowRate()
   end
end
function fuelRodLevel()
   rodLevel = r.getControlRodLevel(0)
   --print(rodLevel)
   m.setCursorPos(30,5)
   m.write(tostring(rodLevel).."%")
   m.setBackgroundColor(colors.white)
   m.setCursorPos(28,6)
   m.write("	   ")
   for i = 1,10 do
	  m.setCursorPos(28,i+6)
   m.setBackgroundColor(colors.white)
   m.write(" ")
   m.setBackgroundColor(colors.yellow)
   m.write(" ")
   if rodLevel/10 >= i then
	  m.setBackgroundColor(colors.red)
   else
	  m.setBackgroundColor(colors.yellow)
   end
   m.write("   ")
   m.setBackgroundColor(colors.yellow)
   m.write(" ")
   m.setBackgroundColor(colors.white)
   m.write(" ")
   end
   m.setCursorPos(28,17)
   m.write("	   ")
   m.setBackgroundColor(colors.black)
end
function turbineInductorDisplay()
   turbineInductor = t.getInductorEngaged()
   m.setCursorPos(30,5)
   if turbineInductor then
	  m.write("On")
   else
	  m.write("Off")
   end
   m.setBackgroundColor(colors.gray)
   m.setCursorPos(28,6)
   m.write("	   ")
   for i = 1,7 do
	  m.setCursorPos(28,i+6)
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   m.setBackgroundColor(colors.lightGray)
   m.write(" ")
   if i % 2 == 0 then
	  m.setBackgroundColor(colors.gray)
   end
   m.write(" ")
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   if i % 2 ~= 0 then
	  m.setBackgroundColor(colors.lightGray)
   end
   m.write(" ")
   m.setBackgroundColor(colors.lightGray)
   m.write(" ")
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   end
   for i = 8,10 do
   m.setCursorPos(28,i+6)
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   m.setBackgroundColor(colors.lightGray)
   m.write(" ")
   if turbineInductor then
	  m.setBackgroundColor(colors.red)
	  else
	  m.setBackgroundColor(colors.blue)
   end
   m.write(" ")
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   if turbineInductor then
	  m.setBackgroundColor(colors.red)
	  else
	  m.setBackgroundColor(colors.blue)
   end
   m.write(" ")
   m.setBackgroundColor(colors.lightGray)
   m.write(" ")
   m.setBackgroundColor(colors.gray)
   m.write(" ")
   end
   m.setCursorPos(28,17)
   m.write("	   ")
   m.setBackgroundColor(colors.black)
end
function getClick()
   local event, side, x, y = os.pullEvent("monitor_touch")
   button.checkxy(x,y)
end
function findOptFuelRods()
   m.clear()
   r.setActive(false)
   checkEn()
   displayEn()
   fuelRodLevel()
   while r.getFuelTemperature() > 99 do
	  for i= 1,3 do
	 checkEn()
		displayEn()
		fuelRodLevel()
  m.setCursorPos(3,6)
		m.write("Finding Optimal Rod Level")
	 m.setCursorPos(3,7)
	 m.write("Core Temp: "..r.getFuelTemperature())
  m.setCursorPos(3,8)
  m.write("Waiting for 99c")
	 sleep(1)
   end
   end
   while r.getHotFluidAmount() > 10000 do
	 for i = 1,3 do
	 checkEn()
		displayEn()
		fuelRodLevel()
  m.setCursorPos(3,6)
		m.write("Finding Optimal Rod Level, please wait....")
		m.setCursorPos(3,7)
		m.write("Fluid Amount: "..comma_value(r.getHotFluidAmount()).."mb")
  m.setCursorPos(3,8)
  m.write("Waiting for 10,000mb")
	 sleep(1)
   end
   end
   r.setAllControlRodLevels(99)
   r.setActive(true)
  
   while r.getFuelTemperature() < 100 do
   for i = 1,5 do
	 checkEn()
	 displayEn()
	 fuelRodLevel()
  m.setCursorPos(3,6)
  m.write("Set all rod levels to 99")
  m.setCursorPos(3,7)
  m.write("Waiting 5 seconds...")
	 sleep(1)
   end
   end
   for i = 1,5 do
	 checkEn()
	 displayEn()
	 fuelRodLevel()
  m.setCursorPos(3,6)
  m.write("Set all rod levels to 99")
  m.setCursorPos(3,7)
  m.write("Waiting 5 seconds...")
	 sleep(1)
   end
   local tempMB = r.getEnergyProducedLastTick()
   print(tempMB.."MB/t of steam")
   local tempRodLevels = math.floor(2000/tempMB)
   print("2000/"..tempMB.." = "..tempRodLevels)
   tempRodLevels = 100-tempRodLevels+5
   print("Adding 5 to Rod Levels: "..math.floor(tempRodLevels))
   r.setAllControlRodLevels(math.floor(tempRodLevels))
   print("Waiting 10 seconds to confirm...")
   for i = 1,10 do
	 checkEn()
	 displayEn()
	 fuelRodLevel()
  m.setCursorPos(3,6)
  m.write("Estimated Level: "..tempRodLevels)
  m.setCursorPos(3,7)
  m.write("Waiting 10 seconds...")
	 sleep(1)
   end
   tempMB = r.getEnergyProducedLastTick()
   while tempMB > 2000 do
   tempRodLevels = tempRodLevels+1
   r.setAllControlRodLevels(math.floor(tempRodLevels))
   print("Setting Rod Levels to: "..tempRodLevels)
   for i = 1,5 do
	checkEn()
	   displayEn()
	   fuelRodLevel()
	m.setCursorPos(3,6)
	   m.write("Getting below 2000mb/t")
	m.setCursorPos(3,7)
	m.write("Currently at: "..tempMB)
	   sleep(1)
   end
   tempMB = r.getEnergyProducedLastTick()
   end
   while tempMB < 2000 do
	  tempRodLevels = tempRodLevels -1
   r.setAllControlRodLevels(math.floor(tempRodLevels))
   print("Setting Rod Levels to: "..tempRodLevels)
   for i = 1,5 do
	checkEn()
	   displayEn()
	   fuelRodLevel()
	m.setCursorPos(3,6)
	m.write("Getting Above 2000mb/t")
	m.setCursorPos(3,7)
	m.write("Currently at: "..tempMB)
	   sleep(1)
   end
   tempMB = r.getEnergyProducedLastTick()
   end
   OptFuelRodLevel = tempRodLevels
end
  
function autoReactor()
   if not steamReactor then
	  r.setAllControlRodLevels(0)
	  if energyStoredPercent < turnOnAt then
	   if not reactorOnline then
	  online()
	  end
	  end
	  if energyStoredPercent > turnOffAt then
	   if reactorOnline then
	  offline()
	end
   end
else
	r.setAllControlRodLevels(OptFuelRodLevel)
	if energyStoredPercent < turnOnAt then
		 --online()
		 setTurbineOnline()
		 coilsOn()
	end
	if energyStoredPercent > turnOffAt then
	  --if turbineRotorSpeed > 1800 then
	  --   offline()
	  --else
	  --   online()
	  --end
	  setTurbineOnline()
	  coilsOff()
	end
	if turbineRotorSpeed > targetSpeed then
	   offline()
	else
	   online()
	end
end
end
function displayScreen()
--  repeat
   checkEn()
   displayEn()
   if menuType == "Reactor" then
	 fuelRodLevel()
	 if mode == "Automatic" then
		autoMenu()
	 autoReactor()
	 else
		manualMenu()
  end

   else
	 turbineInductorDisplay()
  if mode == "Automatic" then
		turbineAutoMenu()
	 autoReactor()
	 else
		turbineManualMenu()
  end
	
   end
	
   timerCode = os.startTimer(1)
   local event, side, x, y
   repeat
  event, side, x, y = os.pullEvent()
  print(event)
  if event == "timer" then
	 print(timerCode..":"..side)
	 if timerCode ~= side then
		print("Wrong Code")
   else
	 print("Right Code")
   end
  end
	until event~= "timer" or timerCode == side
	if event == "monitor_touch" then
		 print(x..":"..y)
   button.checkxy(x,y)
  end
--  until event ~= "timer"
end
if steamReactor then
   findOptFuelRods()
end
while true do
   displayScreen()
end

This code won't produce that error on that line; presumably you've changed the spacing or something and thrown the number off as a result. Doing some web searches, this appears to be a modified version of one of Dire's scripts, but even what I believe to be the original can't error exactly like that..

A quick guess is that you don't have a "BigReactors-Reactor" hooked up to your computer.

now it say reactor:8: attempt to index ? (a nil value)

Again, the eight line of the code you've posted can't produce that error.

What it's saying is that you're attempting to treat an undefined variable as if it were a defined table. Most likely you're getting such an error because peripheral.find() is failing to see a connected peripheral of the types specified at the top of the script.