Cables Question, Help!

I'm working with a marching band that needs some help with a cabling question.  We have a Yamaha TF1 sound mixer with two amps connected to two sets of stacked speakers.  The subwoofer is a Yamaha CW118V and a Yamaha CM15V is stacked on top.  They are using two speakon 12-2 cables to connect each speaker set but no sound is coming from the subwoofers.  I checked everything that I can and when I pulled off the back panels of the subwoofers, I noticed that there are more than 2 poles wired up.  I ASSUME that means I need 4 pole cables.

Can somebody confirm this or am I missing something?  I confirmed the subwoofers work by plugging into the RCA jack on the back.