copyPixels on MovieClip with children


I’m working on my second flash game and have been stopped in my tracks trying to cache MovieClip Animations into arrays of BitmapData frames. To capture the frames I have set up a loop which runs through the frames in the MovieClip and use copyPixels to get a snapshot of the graphic.

This works fine if the MovieClip to cache does not contain any child MovieClips, but if it does, these MovieClips are frozen on their first frames. I’ve been looking at MovieClip.getChildAt(index) in attempt to navigate their time lines but because that returns a DisplayObject it seems impossible. :puzzled:

So, my question is:

Is it possible it to use copyPixes on a MovieClip and also step through child time lines, or should I be using sprite sheets?

Thanks in advance