Need Help With Vandesteen 2WQ Sub

I bought a used, but seemingly good condition subwoofer last month on Audiogon and just finished hooking it up. Problem is that I can't get any sound to come out of it. I'm pretty sure that the cables are in right and that I did what the instructions said with respect to the variable crossover. Is there an on-off swith somewhere that I'm not seeing? I'm starting to wonder if there's something wrong with it. Anyone have any ideas?
When you first plug the sub in after it has sit overnight, you should hear a low level, but solid, thump. If you don't here this thump, the sub is not turning on. It does not have an on/off switch. It turnes on with the power.
If the sub thumps on turn on, I would double check the cables from your amp output to the sub. The filter inserted between the preamp and amp will not keep the sub from working since the signal comes off the output of the amp.
If the sub doesn't thump, make sure you have wall power at the socket.
Mlkiz- The WQ is not a real "thumper" like a traditional HT sub. If you have a more or less full range main speaker the effect is not dramatic. Also make sure you have it in phase with the mains in terms of polarity both with respect to the mains and with respect to the two channels. Also make sure you have the speaker sensitivity set high enough. As an experiment, try maxing that out and see if you have any noticeable output.
For what it's worth, I had a similar problem with my two Vandy 2Wq subs, which I initially plugged into a Monster Power HT2000 line conditioner / power strip. For some reason, neither of the subs were "turning on". I called Richard Vandersteen, who said he was baffled by the problem. After trying several options, I tried plugging both subs directly into a wall outlet, using "cheater plugs to remove the ground. That solved the problem, and the subs "turned on". The only explanation that I've heard that made sense was a reverse polarity problem, as Swampwalker suggests.