I take it that your Set Driven Keys are all animated and that the render options are set to cover multiple frames (1 - <end of animation>). Also are you rendering out a video file or are you doing it as images to composite after? Have you tried a playblast to ensure that everything is OK and that all the animation is working?

Sorry can't really advise much on whats happening until I know more about how the scene is set up. A few screenshots could help to