Time to break out the manuals.
Sometimes there's a setting on the cable box to turn on the digitial output. Likewise, sometimes you have to "tell" the receiver that there is a digital input.
Again, unless someone has exactly the same units you do and happens to be reading this forum, both of these take a little reading of the manuals.
Welcome to the hobby. It ain't plug and play no more.
P.S,.. you're running the TV bodx and the game to different inputs, right?
and, can you get, or did you ever any output from that digital input? If not, and this is a new unit, odds are it's a setup problem somewhere. Those converters are no brainers, assuming the dierctionality is correct. Do you have a known configured and working DVD player lying around for testing purposes?