Some tvs will only run audio out to the stereo or ht system by manually switching external speakers to the on position from the set up menu.
Try running the interconnects from the tv to an input that you get sound from right now like a cd input that you can hear sound from,if you get no sound through a proven active input then you know the tv is hooked up to the system using the wrong output or that there is a problem like switching external to the on position.