What!? Second Function not firing!

Of all the problems in the world. This is by far the one problem I had never expected to encounter.
So when I run this line of code on my advanced computer on my sever.

function on()
  rs.setOutput("back", true)
  term.clear()
  term.setCursorPos(1,1)
  print[[WARNING! CATOSTROPHIC OVERLOAD!
SHUT DOWN SYSTEM BEFORE MELTDOWN!]]
  print("Phase 1")
  a = true
end
function off()
  rs.setOutput("back", false)
  term.clear()
  term.setCursorPos(1,1)
  print[[WANRING! CATASTROPHIC OVERLOAD!
SHUT DOWN SYSTEM BEFORE MELTDOWN!]]
  print("Phase 2")
end
while true do
  on()
  sleep(0.5)
  term.clear()
  print("REPHASE")
  sleep(0.25)
  if a == true then
	off()
	a = false
  else
	print("error...off()")
	break
  end
end

I did not expect I to only half work. especially since I have some nightmare pieces of code ruing on other computers. when I say night mare I men that I have been working on it for so long that I don't know what half of it means only what the outcome is and that it wok everywhere. but I shut them off for now and started coding this simple alarm computer s that I can set off a visual light and sound alarm for when my build craft Kinesis pipes over load I can shut the system down.
Anyways. The code does not return my "endline" function like it was supposed to because it isn't even firing my off() function. I am clueless as to why this is occurring. I am lot and I want to turn on my engines and continue to expand my oil refinery while I transfer liquids to their new silos.

First, you never never declare a, so it never remembers what it was.

I can get it to work by just adding this line immediately after the while:

local a

I see you are using rs.setOutput – but do you know about rs.getOutput?

local a = rs.getOutput("back") -- a will be true (on)  or false (off) depending on state of "back"

Yes, however im teaching my friend code and im trying to keep the amount of terms he learns to a minimum. Trying to teach him simplicity before adding new terms.