HID on audio device

I am making the USB stereo Speaker (L/R Channel) with functionality of HID
which primary focus on Volume Up/Down/Mute.

My speaker only support Master Channel Control; therefore, under the
Feature Unit Descriptor of HID, i set the following:
Master : Mute, Volume up/down
L/R : None

Now, i am facing a problem with HID. It only works under Windows Xp, but
HID fails on Windows 98, Me, and 2K by not responding hardware control,
i.e. pressing the volume up and down hardware button. Also, that testing
environment operates with the default Windows USB and HID drivers.



thanks