Sound cuts out before 1st chapter

HI
I got a Panasonic SA HT700
and everything is fine until it goes to play the first chapter of any DVD we put in.

it startsup ok, sound coming nice and clear thru the speakers
all thru the previews and then when it goes to start the movie
the sound completely goes !
and we have to use the TV sound

Anyone have any ideas?

thanks

90% of the previews on movie discs are encoded in Prologic...so my guess is that if its an all in one package u must enter the settings and adjust thigns. If you have a dvd player sepperated from the receiver, you must go to its setup and adjust things from there. Please keep in mind that you need a coaxial or Optical wire to make a DIGITAL CONNECTION. without it you cant playback a dolby digital or a dts signal. (Perhaps the dvd you where trying to play was set on dts and your amp doesn support it)
Try while playing any movie to change its audio output to Dolby 2.CH (AUDIO Button on the remote)