Masking problems - animated mask over color

Hey guys, so i’m attempting a neat little effect where i’ve got a fellow walking (already drawn and animated) and i’m using him as a mask over the top of a simple colored rectangle - the idea being, by changing the color of the rectangle, i can have a walking man with color effects happening. At this stage the square is just green, because the mask is not quite working correctly. The edges of the animated mask glitch up and don’t work as expected.

I’ve attached a copy of the .fla in a zip file. Hope you guys can view it and let me know why masking it might make it glitchy.

Cheers!

-PT