Prob with masking

i have this pic here which i use a circle to mask. then another pic will appear in front of it using the same effect. but only the first pic works. the 2nd pic doesnt. anyone has a solution?
the effect is similar to this site: [color=#800080]http://www.infineum.com/[/color]

make a movie clip with ur mask effect (the three circles in that site’s case that reveal the images). put image one in the timeline with the circle mask over it, put imgage two down further with the cirlce mask over those frames, etc with as many images as you want.

this is not very efficient as you have to tween all animations out but it will achieve the effect u want.