Issues displaying image with guiHealthArcHud

I'm working on implementing the RealmWars guiHealthArcHud, but I'm having problems getting it to display my images. I've got it compiled into the engine, but when I put it in my playGui.gui file, it doesn't display the .png file associated with the gui element. Am I supposed to be using a png or other image file? If not, how do I display fill color of the arc hud?

Thanks,
Denise