Just to run through the array of stuff... Make sure you don't have any loose cables (mainly thinking of sub interconnect). Make sure your source material has low frequency material to send to the sub (test tone discs like my Devious Tiny Disc would do this). Make sure the sub's turned on in the 950 setup and that your other speakers are set to small. Make sure the sub's plugged in and set to either "on" or "auto." If it is set to turn on automatically, make sure the gain is only about half way up (so that the 950's sub trim can be set high enough to provide enough signal for the auto-sensing circuit to react).