Re: Strange Issue with Expression Control Effects and Precomp

By "not working", did you mean that after you add a key frame of the slider control, sliding it won't affect the rotation of the earth as it used to when it doesn't have the key frame?
Then this must have been because the actual value out of this slider control is overridden by the key frame. It makes sense - when you use key frames, you want its value to be controlled by the key frame, not what you manually told it to be. So the earth doesn't rotate because you only have one key frames -- one key frame means constant value throughout the time. Have you tried using two key frames at the beginning and end of the time? You should be able to see the earth rotating between the angles specified by those key frames.

Xinlai Ni
Software Engineer, Google Inc.