Masked progress bar UMG

We’re trying to figure out how make this (see image) work. Basically what we want is for the foreground (black thing) work as a mask so that it shows what’s under it (the green bar)

http://puu.sh/dm6km/f69a621b27.png

wouldn’t think it mattered as it is 2D.
you can use the green as the background and the black as the fill image and reverse the values in the progress bar.
or make the green bar an image and make the Zorder less than the Zoder of the progress bar with the black thing as the fill image and again play with the values.

if its because the green texture is smaller than the black, remake the green texture to be the same size as the black but with a transparent (alpha) top and bottom edge.