hey dan,
thanks for trying. i tried in another comp an there it worked well. may it be, that when the main project is getting to big, ater effects won`t handle this anymore? or is there something like general expression settings where i may have changed something unluckily?
i don´t get any error messages from the expressions. and when i set the first keyframe, and work on this time-position, the expression does what it should. only when i try to make a keyframed animation, it stops working proper.
thanks a lot! jan