I'm experiencing problems getting a Dolby Digital 5.1 signal via optical to my Cambridge Soundworks DT3500 on certain Blu-Rays. I've tried all the different setting I think are possible for the optical output. Strange thing is the menu's and trailers on the Blue-ray do come through my surround sound in DD 5.1 but when I get to the main movie the LED that indicates a Dolby Digital 5.1 signal goes out. The DT3500 is quite old and does not support the new HD formats or DTS just the old Dolby Digital 5.1. Are the new Blurays not carrying the old standard DD 5.1. The movie was 'The day the earth stood Still' and in the sound menu on the blu ray only had a option for 5.1 DTS HD.