Is it possible the display on/off also controls the blue wire? I see some stuff in the FAQ that seems to indicate there is some connection there.

For right now I have the display off because I don't yet have the code for it and I don't want it to burn in. Maybe I will try blanking the screen but leaving the display on.

edit: Ah-ha, yes that's it. The display power is 'tied' to the blue wire. Now if I could figure out the volume. It looks like /dev/mixer supports the standard ioctl MIXER_WRITE(SOUND_MIXER_VOLUME) so I'm not sure why it's not working.