I just bought a Yamaha Receiver (RX-V375), that has both RCA, HDMI and Cable Coax Connectors. My DVD player is a Sony model , that only has the digital coax connectors or HDMI output. My tv doesn't have HDMI but does have RCA connectors. So far I've been able to get sound from the DVD but no video on the HDMI. Nothing on the Coax. I have the cable box plugged into the receiver, and I get picture and sound on that. What am I missing here?