Mask effect problem

Hi guys,
I’m creating a mask effect. i create 10 movieclip with a library class reference that appear on the screen with a random alpha effect. THe problem is that if i try the effect alone all works ok. if i mask the layer that contains the effect on an image i don’t see the effect. i see directly the image masked with the boxes. i can’t explain that because i’ve the effect first but it seems that when i test the movie the effect doesn’t play and the boxes appear directly on the screen.
Here the file: http://www.megaupload.com/?d=DVKVWXXE …please help me !!!
i advise you to run the file without the mask first to see the effect first.

(the image is in the library).