this was touched on earlier, but your reciever's digital inputs need to be configured, for example, on my denon avr-3806 i have to assign my optical digital input from the cable box to the same input that the video comes through, your best bet is to make sure your cable box is set to output a digital signal through the cable box menu, and go to your receiver and switch to the input your video comes through, run through the digital audio input assignment in the setup menu, and cycle through, ex. your cable is set to video 1. set the cable box to digital out through the menu, and cycle through the inputs, digital audio input 1, no sound, digital audio input 2, still no sound, do so untill you finally get that sweet sweet digital audio through that equally sweet receiver.repeat with dvd player