Capturing screens as images using PrintScreen?

[jarvis24]

[edited from support email]

I need to be able to obtain an exact image of what DirectRT presents to participants so that I can use it to draw Areas of Interest that we need for our eye tracker. The tracker manual suggests we use PrintScreen the command and paste this into Paint to make .bmps, however, DRT will not allow us to do this... When we do try this method, we get only a black background without the image. We also tried using some MS software to capture the image but that too didn't work. Any ideas? For some reason, when we compare the location (not size) of images produced separately from the different sources (in Paint and DRT), they do not line up precisely. So it seems that the PrintScreen approach would be very useful.