Subwoofer problem


I have problem with my B&W ASW 800 subwoofer with Rotel RSP1068. Just started not working. Both of them are brand new.

Just want to try more before I bring it to place where I bought since subwoofer is so heavy.

When I do the speark Test Tone from Rotel 1068 processor, there is no sounds in subwoofer, all other 5 speakers are fine.

But when I switched off the subwoofer for a while then turn back on it, hear a sound for a second then nothing. However not everytime I turned it off/on again, just sometimes it works momentariy but not always. so I think it's not the cable I think. Also I see green light at the backside so power is o.k.

Thse are my subwoofer settings,
Volume:12 o'clock position.
Mode: ON
Phase switch: 0
Low-pass filter: OUT
Low-pass frequency: irrelevant(use for home theater) but I set it somewhere between 80~100hz

Rotel RSP1068 processor settings,
Speaker setup: small to all (Front, Center, Rear)
subwoofer: Yes
leave dB as 0 (default)

So Can you tell me what I can do to diagonosis?

I'll really appreciate any feedback.

An easy way to check is to run all your speakers as full range, and connect some speaker wire "speaker level" to your sub from your main amp/speaker posts!!! (so you're not connected via "line level", bur rather "speaker level") I believe your sub has both speaker and line level connections, yes?
IF the sub works, then it's a connection/internal setting problem from the rotel likely. Otherwise, a connection problem at the sub. Another way is to get a nother little sub and try it. If it works, then it's your sub!!!
good luck
I have a Rotel RSP-1066, and it does not send a test tone to the subwoofer, so don't worry that you are not hearing one. Try setting your subwoofer setting to MAX instead of just YES. This will make sure that it is being fed a signal regardless of crossover point. Also, are you using one or both of the subwoofer outputs? If just one, then try the other. Another possibility is that the signal is too low for your sub, and the auto signal sensing keeps turning it off. If you can, set your sub to ON versus AUTO. Also, try either using two interconnects, or boost the sub signal up to +3 db or so, to make sure that you are getting a robust signal to the sub.

Good luck, Tom.
Many processors don't send a signal to the sub. I friend of mine has the top of the line Yamaha and hers doesn't send any thing to the sub in the mode you speak of.
Does your sub operates with other sources. You might have to set it up with a test DVD such as Video Essential or on some movie or concert DVDs there is a THX optimizer chapter with audio test tones.
Good luck.