1 - You may have a bad cable. try switching the cable.
Let see if I get your connection right. DVD/BD Player ------> Surround Sound System ------->TV
2 - TV is probably not set up for HDMI
3 - Do you get audio signal on the TV from your DVD/BD Player? if yes, check TV video settings.
4 - Try other HDMI port on the TV.
5 - Unplug TV power cord and plug it back in.
6 - Are you playing DVD disc or BR disc, does both have the same issue?