I saw your earlier post and just now noticed something.
How are your connections set up? Are you running an optical TOSLink cable from the DST-3000 to your audio receiver? Have you checked the rca L/R outputs to see if you get sound from them? How is your receiver set?
As I posted earlier, my DST-3000 is currently set to DD out and everything sounds fine. In other posts I've seen on this forum and the DBS forum, DirecTV did have some DD issues with HBO last week that apparently have been corrected. This might be what the DirecTV CSR was referring to.
If you are not currently getting sound, then there is either something wrong/quirky in your setup or you might have a defective piece of equipment (DST-3000 or audio receiver). Again, did you run the experiment of moving your DVD player's TOSLink to the input you use for your DST and verified that that works (or vice versa)? If so, then I think there could be a problem with your DST-3000 unit.