Mask doesn't work when exported? Please help!

Hi guys,

I have a big problem… I’ve done this super long animation and all has been well untill i exported it. The masking worked fine when i preview it by playing the playerhead. But as a swf, the mask just doesn’t show up. The masked area and the masked thing just “disappears”, a blank space replaces the images. This is really fustrating as i have done masking before and this had not happened before. I am hoping that someone has encountered this “bug” before and could tell me how to solve it. I really don’t wish to re-do the whole animation again as it will take a bloody long time. When i view the animation with my playhead, it still works and i can see the masking done… Just when exported, it doesn’t… =[

Many thanks in advance!