A couple of shots in the dark too as I've played with Tk but never done any animation in it.
- Does the animation need to be packed in some way? That's bitten me more than once when I thought something should have shown up, it wasn't packed.
- You are calling MainLoop aren't you?
HTH!
Useless trivia: In the 2004 Las Vegas phone book there are approximately 28 pages of ads for massage, but almost 200 for lawyers.