The HT-C6930 (U.S. model) doesn't have ARC, and I think it's that way feature wise in your region also (although, the Samsung customer service center should be able to clear that up if there's still a question).
The TV is right, the cable is right, but the HT system doesn't support ARC, and all three components needs to be able to take advantage of that technology.
Optical audio would be the next best thing.
I have the combination home cinema system HT-C6930W with TV UE40C7700. For data exchange I connect them together with a HDMI 1.4 cable on the usb port 2 (with ARC - audio return channel) of the TV. I also use the included sat receiver of the TV
When I want to hear the sound of a TV program over the home cinema system - nothing all quite. I test also all settings on the TV without sucess, no information on the Samsung homepage also in the documentation.
My question is:
Can the HT-C6930 receive sound informations over the HDMI 1.4 cable or is a additional optical cable between these two Samsung components necessary?