Disklavier

Subject says it all...  Is there a way to disable the movement of the keys when I'm using MIDI to play the Disklavier while in Silent Mode?  I plug in headphones, which of course blocks the hammers, but the keys still move -- and make quite a bit of noise when playing back "loud" music.  (I say "loud" because I have headphones on.)  Under the Setup menu of the PRC, there's an option "QUIET KEY:" which can be on or off.  It seems that "OFF" should disable the keys when the piano is playing back (via MIDI) in quiet mode, but it doesn't.

It's great that I can go into quiet mode, but with the keys bouncing all over the place, it's not really all that quiet!  Is there some setting I'm missing?  Does the "QUIET KEY" setting only apply to silent playback from within the Disklavier itself?  (If I play a track contained on the Disklavier's hard drive, the keys don't move.)
Thanks!
-John