I think I know what the problem is, but I'll get to it in a second. You need to make sure any input using DVI is set to use the specific DVI connection that you hooked the source to - until you do that, the 990 won't know to use that input. I don't think this is your problem, though, because you didn't mention connecting any source components to the 990's DVI inputs.

The 990 will not convert analog video sources to digital - this means that composite, s-video, and component inputs are not available at the DVI output. I'm guessing that the video1 input is using an analog video source.