hdmi arc not working

My connection details HDMI out(ARC) from home theatre(Sony HT IV300) to TV(Vu QDV65)'s HDMI1 ARC My Airtel DTH's HDMI out to TV's HDMI 2 *There is no direct connection between the Home theatre and the Airtel DTH As stupid as it may sound, if I turn off my Airtel DTH, and I'm playing some...