Which ports should my front speakers go into?

I have a 2807 that has a front a and b hook up. and have a right and left for both.. The pictures in the manual are a little confussing, should i hook both polk rti10's to the same hook up(a) or should i hook one speaker up to the a port and one to be b port. (when i seem to do this one speaker does not work)

thanks for you help