Help.. loadMovie with a mask

Hi,

I’m using the loadMovie function to load a movie into a layer which has a masking layer on top. When I play the movie, the loaded movie appears for a few frames and then dissapears!? This seems to happen where a keyframe is in the masking layer. also, when I get rid of the mask it loads fine.

if someone might know the answer to why this is accuring then that would be really really helpful! Cheers