Sound volume not controllable with mapped buttons

Binary package hint: xmodmap

I have a Logitech USB headset.
When I plug it in my computer it is automatically selected as the default sound device, which is a great feature. ( controlled by asoundconf I think ).

Problem is, if I use the buttons that are on the headset, I should be able to change the volume of my headset. This is happening, but the problem is that the OSS microphone volume is changed and not the volume of alsa.
In Volumecontrol I can see the slider of the USB Mixer ( OSS Mixer ) - Microphone move, but that's the wrong one.
Effectively this is doing nothing because my headset uses alsa.

The same thing happens when I use the volume up/down buttons that are on my chicony keyboard.

I've already set up the buttons correctly via System-->Preferences-->Keyboard Shortcuts but it seems that the package/program that is controlling the sound ( xmodmap? ) controls the wrong sound program.

Xmodmap should use alsa, or there should be a possibility to select alsa or OSS when configuring the keymaps.
I'm not sure this IS a xmodmap problem, could have something to do with the gnome mixer controls too.
Another cause could be that Gnome doesn't choose the right mixer device for the XF86Volume* bindings.
I'm not an experienced developer so I don't know where the problem lies.

I'm running Ubuntu 6.06 LTS.
Version of xbase-clients: 7.0.0-0ubuntu45