Receiver will not play both sets of my speakers. What gives?

I recently acquired a Kenwood VR-410 receiver to run 2 sets of speakers I have (8 ohm, Kenwood KL-888x and 8 ohm 35watt Sony SS-510). Both sets are 8 ohm speakers and worked fine on my old amp that fried. I have tried every configuration and channel and the Kenwood speakers play in any while I the Sony speakers are dead as a doornail. Am I missing something here? There is no impedance problem but the Sony's will not play in any channel. Is there a fix to this?