Frusterated with failed subwoofer hookup

Alright, I have a 5.1 setup in my theater room that I'm working on. Using a Harman Kardon AVR-2600, with 2 bookshelf B&W DM602 S3's up front, a center channel, and a couple of ceiling surround speakers in the back.

I bought a Pinnacle Baby Boomer sub woofer on sale after reading some nice reviews on it. My room is 9' x 25'. The fronts, center, and rear speakers all work great. My sub woofer powers on (and makes an audible noise within its box, so something is happening in there) but after about 5 minutes it goes into standby meaning it isn't receiving any sound signals. What the hell...

My two front speakers are using jumpers to connect the hi and low fidelity ports together. I've checked all polarity's to make sure I've got my + and - all correct. I used the supplied cable to connect the sub woofer to the "sub" port on the back of the AVR, but cannot get any bass to come out of the dang thing.

I've tried adjusting the AVR settings the the "Manual Speaker setup" but to no avail. I tried the "EZQ Autosetup", but it never detects a subwoofer within the setup.

PLEASE HELP! I have scoured the forums, done due diligence with google searches, but I can not find a fix for this.

Oh wow, after all my nights of troubleshooting, all the time searching for this answer, I think u might be right. I never saw that output jack as it is really hard to get to it where my receiver sits. I just assumed there was only one purple sub jack. I will try that out over lunch and let ya know. Thanks and now I feel like an idiot. Haha

It worked, haha. Thanks!