Backlighting an image

Hi Guys, I am using Accurender NXT and have been for a few years now. I am currently doing interior renders and want to show a back illuminated picture, however I can't seem to get this to work, see the enclosed image, they just seem to appear black. I have the lights set back from the image and have used Alpha color mask on them, but the rest of the images dont seem to render.

Can you help?