No speaker Sound when using Optical Digital cable or Iinfra red cable

I think it's just an encoding incompatibility issue and not that something is broken. You're using the encoded output from one of the newest TV's into the input of an older Denron receiver. There's a couple of ways to get around this. You can either fork out for a converter unit that handles the TV encoding and outputs into something basic, or you can use other cables and inputs, like HDMI or digital coaxial or even good old analogue. The HDMI might also be incompatible, but you can run it through a cheaper splitter that can deal with the encoding format of your TV. I'd use cheap RCA cable just to prove a point first.