Audio short

I have have 2 audio ouput sources that connect to a Yamaha RX-397's AUX[Switcher] & CD/DVD[PC] RCA inputs; (1) program audio out from a 6x2 switcher & (1) PC Audio out from a Dell Optiplex. When my Bluray player audio thru the switcher is playing as it should, I try to connect the Pc's audio and...