Angry birds attempt to index failed error

Hi guys,
I have recently started playing Angry Birds and I also watched a video on how to create the level. I copy pasted the codes into wordpad and by doing so I replaced the Level 1.Lua file. Then I started Angry Birds level 1 but the following error appeared on my screen. The screenshot of the error is as follows:
He error says:
Error
?:0: attempt to index failed? ( A nil value) (call stack not available).
Can anyone please explain how you solve the issue? I'll be really grateful.
Waiting for your reply.
Regards,
Jones
