Gradient mask and external movie problem

programming flash
1

Hi all,
I have a movie that has a gradient mask in it:

sketch2.cacheAsBitmap = true;
sketch_mask.cacheAsBitmap = true;
sketch2.setMask(“sketch_mask”);

It works just fine until I try to load it externally into another movie. Any reason why this is and how I can fix it?

Thanks,
renis