Can someone help me out with this?

Hello first of all. My favorite mod is redpower and I started to like computercraft aswell lately. Unfortunatly I'm not really an expert with coding, and I've made this small program but when I try to run it, it says "Attempt to call nil" I don't really know what that means and/or how to fix it. Me and a friend of mine set up a server together with houses close to eachother but with a pretty big gap inbetween. I made a retractable bridge using redpower and wanted to activate it using computercraft.
And this is what I came up with:

redstone.setOutput("back",true)
mon = peripheral.wrap("left)
mon.clear()
mon.setTextscale(1)
mon.setCursorpos(1,1)
mon.write("Bridge extracting…")
sleep(10)
mon.clear()
mon.setTextscale(1)
mon.setCursorpos(1,1)
mon.write("Bridge extracted")
redstone.setOutput("back",false)

Thanks in advance and excuse me if this is in the wrong discussion.

instead of mon, use term.

ie.
term.clear()

Also. its write("") not mon.write.

 
redstone.setOutput("back",true)
mon = peripheral.wrap("left")
mon.clear()
mon.setTextScale(1)
mon.setCursorPos(1,1)
mon.write("Bridge extracting...")
sleep(10)
mon.clear()
mon.setTextscale(1)
mon.setCursorpos(1,1)
mon.write("Bridge extracted")
redstone.setOutput("back",false) 

You forgot a few "'s and capital letters like mon.setTextscale(1) should be mon.setTextScale(1)

Also wrong place, should be in ask a pro

Thanks a ton both of you! Also I'll remember to post in the right section then for next time.

rhyleymaster, on 26 December 2012 - 11:26 AM said:

instead of mon, use term.

ie.
term.clear()

Also. its write("") not mon.write.

Please don't attempt to answer questions when you don't understand the code involved.