Audio System layout

Can someone tell me what's wrong with this setup (I hope you can read my diagram)?

I have two 4-channel amps, two 10" subs, rear 5.25 and front 6.5 components. In the diagram (if you couldn't read my diagram or figure it out):
XO = crossover
FT = front tweeter
FW = front woofer
R = rear

I was going to run the fronts and one sub bridged off one amp, then the rears and one sub bridged off the other amp. As of now, only the right sub is putting out sound (and the diagram is correct - two positives connected. +/- didn't work). Also, the sub pre-amp out isn't connected because it didn't make a difference. So, the one sub that's playing is apparently getting it's source from the rear, but I don't know how!

Anyway, could someone lend some insight here?? I'm about to hit the road for Minnesota (from Texas) so I won't be working on it again until I get home, but would like to get the discussion started.

Thanks!

 

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