Samsung HL-R6168W must use internal mute for surround sound?

Hi guys. I have a Samsung HL-R6168W that I'm using with an Onkyo 502 for 7.1 surround. For some reason I have to turn "internal mute" on in order to get any sound out of the 7.1 speakers. In other words, I can't have both the tv speakers and surround speakers on at the same time. Is that normal? It's kind of a pain to have to get into the menu and do this every time I wanna watch a movie, then have to switch it back afterwards.

Thanks in advance!