Need help with dynamic masks!

hey guys,
i’m having an issue with this file
http://www.besiex.com/mpryke/demo/

seems as though my masks just stoppped working when embeded in this html,
i seem to have the same problem if i load the swf into a movie clip on stage, but it works fine when loaded via loadMovieNum and is loaded into a level,

all my masks are set using setMask() method, with bitmap caching turned on via action script,

any light you guys could shed would be great, thanks so much,