Bitmap rendering problem guiHealthArcHud

I've integrated the guiHealthArcHud code, and the arc code works correctly, but I'm having problems getting the bitmap associated with the control to render correctly. My original bitmap (a png file) is 148 x 148, and thus I've made my control the same size. What happens though is my image is scaled down and placed in the lower left portion of the control box. Does anybody have any ideas on how I could remedy this problem.

Thanks,
Denise