Just got a Yamaha RX-V2500 and hooked it all up. I had component and rcas running from my HD cable to the receiver. Decided to upgrade the audio to Toslink. The cable plugs into my cable box with no problems but I can't get the other end to go into the reciever. I tried the other optic inputs but it does not seem to fit there either. Any suggestions? I am sure I am not doing something basic.