Day 004 Gradient doesn't animate.

I just started following along with the stream and haven't had any problems with the code until now. My code doesn't animate the gradient. It starts up a black window and doesn't show a gradient at all unless I drag it off screen partially. Even then the gradient doesn't' animate regardless. I've compared my source to the Day 4 zip file and didn't see any differences. Can anyone make a suggestion as to what might be wrong. I don't know if I should post my code or not?

Edited by B on
If you don't know, you can use the diff command or a gui diff program to compare the zip source with your own.

Any differences you didn't notice should pop right out.
Thanks this helped. I had put in an "=" instead of a "-" on a single line. I didn't catch it the first time glancing through because they look so similar. The diff idea helped a lot.