What model is your Directv receiver/DVR? How are you feeding the signal from the DTV receiver to the sound bar? When you say "it doesn't work" what do you refer to? If lack of Dolby are you sure you're on a channel that provides Dolby and do you have your HD receiver set to "Dolby on"?
Where do I find the Model #. It might be R-15-100. DirecTV Plus, Dolby Digital. The sound bar is connected to the TV w/an Optical cable. The DVR is connected to the TV w/RCA cables (I guess). When I say it doesn't work, I mean that sound doesn't come out of the remote speakers or sub woofer.