It might be your DVD player. It depends on how you have it hooked up too. If you're using digital coax or optical, the 1050 will detect what type of signal it is being fed. If it gets a 5.1 signal, even if only 2 channels are used, it will display dolby digital. Your DVD player probably has settings for output type for DD and DTS. Either bitstream or PCM. This is to allow for older receivers that couldn't decode the signal. You want bitstream.
I just bought a new DVD player, Panasonic CP-72, and when I played a DTS movie I wondered where the surround sound went. The default for DTS was PCM, so I only got dpl. I changed it and voila! BTW, the panny player is superb. Great picture, much better than the panny it replaced.