Coding error.

[deanhystad]

I am coding exactly as it is coded in the example

It is so cute when new programmers say this. You don't know what to look for, of course you cannot see the error you made. Unless you copied the example and pasted it in your file, you made a transcription error. It is nearly impossible not to. Probably an indenting error.

Next time, post the entire error message, including the trace. This usually includes enough information to identify and correct the error.