If you have a source without a .1 track and all of the speakers are set to large, you will not get a signal at the subwoofer output. The 950 is doing exactly what you ask of it. You have two options:

1) Play an x.1 source with the subwoofer on. This will give the bass shakers a signal. Drawback: until the sub arrives, you will feel but not hear LFE tracks.

2) Set some speakers to "small" so the bass shakers get a signal. The Polk and Velodyne subs we discussed earlier would actually be well served by a 40Hz crossover, although the surrounds wouldn't generate much below 40Hz for the bass shaker in most cases anyway. I assume you don't want to do that for your fronts. You still won't hear whatever gets steered to the bass shakers until the sub gets connected to the LFE.