Just got the Toshiba 520E, DVD-video section is very good. But when i put The DVD-A (The Corrs in Blue), can't get D.D.5.1 signal output from my Yamaha AX630. My audio connection is using a optical cable. Why it only comes out stereo sound?When playing the disc, i checked the audio output from the DVD player, it shows 6-channel signal . Pl. tell. Thanks.