Animation not ending

TGB is starting to make more and more sense to me, but I've spent a few hours on a topic which I think shouldn't take more than 10 minutes.

I've created a new t2dAnimatedSprite (with the Config of a t2dSceneObjectDatablock), and within that I am trying to play an animation. The problem isn't the playing, it is the stopping. I can play whatever animation I want with playAnimation(), but getIsAnimationFinished() always reports 0, even when the animation has repeated many times. I'm calling the animation with:

%this.Owner.playAnimation("spawnAnimation");

This is in a behavior. I'm sure that it's something little that I'm missing, but in all of the tutorials that I've seen it looks like this is what they are doing.