[Help] ComputerCraft attempt to index ? (a nil value) error

[buildbob49]

when i try and run this program I have created it says button:6: attemptto index ? (a nil value)
Help please?

Code
http://pastebin.com/hbuvd4k0

 

[Symmetryc]

Rather than doing "button.<stuff>" do "buttons.<stuff>".

 

[buildbob49]

Rather than doing "button.<stuff>" do "buttons.<stuff>".

Thanks it helped greatly

 

[woute65]

hey guys i have the same error but cant see my fault i also want to do the same with my code. i use dw20's api (http://pastebin.com/1iwuzsh8) and this is my own parial code.