Monitor issues...

Hi…
My name is adam, And Im just new to Using computercraft.
I am trying to use the monitor, though It keeps on saying
Startup:4: attempt to index ? (A nil value)
Here is the code i use:
http://pastie.org/pr...gigascfdd9uukdq
(I reached max on pastebin)
Please help!
Adam.

Is the monitor at the front of the computer? I'd assume you meant back :)/>

The sides of a computer are relative to you when you've placed the computer or looking at the screen texture. So 'front' is closest to you, 'back' is furthest, 'left' and 'right' are your left and right respectively, and 'top' and 'bottom' are fairly hard to confuse since you cannot place a computer upside down.