Problem with DVD analog inputs

The main reason I purchased the 970 was for the DVD analog inputs. I have conected my computer to the 970 via MOTU 2408, which is a high end 8 ch A/D D/A converter. I am only geting output from the front channels. I have configured the DVD input, and tried different surround modes with no luck. I have pluged the rear channel outs from the 2408 directly into my amp to be sure that I have output. The manual says that you should not use the analog ins with no DVD-A or SACD capability. I am not familiar with DVD-A, but I don't think I have it. The reason I can't use a digital out is that I mix in surround using Sony Vegas software that only has analog outs for surround (digital out is stereo only). Does anyone know if my gear is compatible? Thanks in advance.

If you are only getting the front left/right inputs, my first thought is to ask if you have selected the 7.1 Direct input? To do this, you press the "7.1" button on the remote. The DVD input uses the analog left/right channels only.

Thanks alot! That did the trick.