infinity kappa, chevy cobalt, a problem?

Today I installed some infinity kappa 6x9's into my 2008 chevy cobalt. I put them in the rear deck. I had some strange results. When I had both speakers just set in their respective spots not secured they played fine. The trouble started when I screwed them down. One speaker played normally, the other acted as if it was getting no power/signal whatsoever. I repeat, this only happened when screwed down tight. If the speaker was just sitting there in the slot it played as usual. To troubleshoot this I tried plugging in the old speaker in the spot and it worked. After that, I checked all connections and confirmed they were not the issue. Afterwards, I swapped the spots the speakers were in to see if that was it. It wasn't. No matter what side I have the iffy speaker put on, it will not work when screwed down. One last thing I noticed was that the speaker that is having problems would make a popping sound when I turned on my car (when screwed down). Thank you for your ideas.

sounds like when the speaker is screwed down the voice coil is touching the side of the magnet. This is probably due to some torque placed on the frame of the speaker when screwed down, or just a manufacturing defect, i would send them back and get a new pair.

I already did that. =] I was just wondering if anyone had any clue why they would act this way. ... I hate when people send me defective stuff then make me pay to fix the problem. Haha. Thanks for the reply