Audio Out on BeagleBoard

I can’t get any sound from my BeagleBoard. I can’t find any instructions on this in “How to get started with a BeagleBoard”, perhaps I have missed something.
I know the AUDIO OUT has worked with the audio cable plugged into a monitor AUDIO IN socket; but this isn’t working with my monitor, an Iiyama ProLite B2409HDS. I haven’t bothered with sound before, but now want to get it working for use with Chris Gransden’s MPlayer.

To add to my own post, I have now managed to get sound by connecting the BB to a pair of ‘computer speakers’. But I still don’t know why I get nothing when the AUDIO OUT is connected to the AUDIO IN of my monitor.
On the monitor I have the volume at 100%. Aha, I had to set the audio on the monitor to LINE IN instead of HDMI; but the sound is very faint. The monitor’s configuration was on auto, so I don’t know why there was no sound before.
The sound from the pair of ‘computer speakers’ is loud enough.

On ‘Sound’ in the Boot Configuration application, everything is greyed out except Headphones (red bar on full) and System (green bar full). Is this as it should be?

Could the sound be quiet out of the monitor because the levels from the audio out of the BB are for headphones, rather than the (louder) line out level?

My BB-xM has always been connected via line in, no problem with the monitor. I use DVI-D however instead of HDMI. Perhaps the monitor expects audio to be carried over the HDMI connection? Be sure to firmly push your audio cable into the BB’s socket. There should be an audible “click”.