I have an old Sony STR-AV720 receiver and a new Samsung UN65JS8500 TV. I want to play TV sound through the receiver. A prior search of forums indicated that I needed a device to convert the TV's digital audio to the receivers analog audio. So I bought a converter, connected an optical audio cable to the TV's mini One Connect box and to the converter. Then, I connected RCA plugs to the converter and to audio inputs on the receiver. I powered on the stereo, converter and TV, and switched TV sound to the optical output, and NOTHING, no sound. What am I doing wrong?