Chris Brown

Need help with subwoofer, pretty frustrated.?

I know the sub works because i hooked it up to another amp and it played.
I know the amp has power because the little green light is on.
I have RCA cables plugged into channel one (white) and channel two (red).
However, I only have speaker wire running out of channel one on the amp because I only have one sub.
When I use a voltmeter on the channel one outputs, I get a positive reading.
Then, when I attach speaker wire to the outputs, I get jack squat (sound and voltage).

I have been looking at this for like 3 days now, and its starting to get pretty annoying.

Please, please tell me what’s wrong?
Is the amp broken?
How can I tell?
I don’t have access to another sub to test it on.