No sound on TV when connected to AVR via HDMI 1.3 cable

Hello,
I need some advice. I just bought a Sony STRDH710 7.1 channel AVR. It has a HDMI (ARC) outlet connection to TV. I have a Sansung 42" flat panel LCD TV. When I connect the AVR to the TV with a standard HDMI cable, the video from a DVD source plays but there is no sound coming from the TV speakers. The sound on the AVR speakers are fine. I tried direct connection of the source to the TV. The sound comes out in that case. What may be the problem? And how can I fix that? Do I need a high speed (later version) HDMI cable to make this work?

(1) Given that you have a receiver, why would you want the TV speakers on ? (I can think of a few reasons, but most people who connect a device thru a receiver want the sound to come from the receiver)
(2) What would Sony expect the majority of people to want? I suspect it's TV video on TV and Sound on Receiver as the default. You wouldn't want sound on both -- they would have different delays and give you an echo effect.

Take a look in the menu system of the STRDH710 and try out the "HDMI pass through
[PASS.THRU] ON, AUTO, OFF OFF" parameter and force on. See if that makes a difference. The manual says the default is Off which is what you'd expect. I have no clue what 'passthru' actually does, but it sure seems like it shoudl be passing the dignal thru to your TV rather than processing it.