Need help with subwoofer on Prism 24G

[JimmyRV]

For the life of me, I cannot figure how to get sound out of this. Jensen subwoofer connected to Furrion unit. Its powers up fine when the radio is turned on, but button C does not cause bass to come through. Some thread suggested it only works with a dvd, I tried that but no luck. I pulled it out to access the controls, set those on max but nothing. All the while the blue light on the subwoofer stays on. Anyone? Thanks.