Sound/volume control problem

I'm running 6-CURRENT/amd64 dated Wed Jun 22 11:41:19 PDT 2005, using a
Soundblaster Live! sound card.  I have "device sound" and "device
snd_emu10k1" built into the kernel.  The card is detected by the kernel,
and the sound appears to work just fine.  The problem is the volume
control doesn't work.  XMMS for example, gives me this error message when
adjusting the volume (mixer: vol):

WARNING pid 88402 (xmms): ioctl sign-extension ioctl ffffffffc0044d00

And when telling XMMS that volume controls pcm rather than master vol:

WARNING pid 88405 (xmms): ioctl sign-extension ioctl ffffffffc0044d04

In an attempt to rule out XMMS as the problem, I also installed mplayer. 
Mplayer doesn't spit out an error message when adjusting the volume, but
the volume stays at a constant level.  I've checked the output of mixer,
and that sees the volume changes, but doesn't actually adjust the volume.

Is this a FreeBSD error, or a user error?  Is there anything that I could
try to fix the problem?  Thanks.

  Ryan