Problem with sub woofer

I just bought a paradigm PS-1200 subwoofer. It is place on the side
walls in front of the right front speaker as it was the est location of
the room where bass was  not muffled.

Following the indications on the user manual i calibrated it with a
music cd.  As i have a Onkyo TXSR 800 i noticed that crossover and
phase aligment control did not produce the expected result as stated in
the manual. I am not sure if it is because the TXSR 800 is THX
certified and has the crossover set to 80 HZ .
Bottom line when listening to music the sub is working fine i can hear
the base coming from the front speakers but with tv watching all the
sub is doing is rumbling , rolling and  the bass can be located to the
sub not the front speakers ..any ideas on what could be the problem

Alain