Try listening with the receiver set to "5-ch stereo" or whatever the units equivilent to that is, & see if the surrounds are producing good sound. If you try to listen to a stereo production in a 5.1/DD format you won't get much if anything from the surrounds. Be aware that even when watching a movie in 5.1/DD that there isn't going to be a constant flow of sound from the surrounds, only when the soundtrack of the movie dictates.
I'm assuming,since I didn't read your other post, that you have the proper interconnects (dig coax,toslink) for the DVD player to the receiver.