Thanks rickenbacherus for your answer.

Still it does not work, but I have found the reason.
I'm using VMWARE WKST to host my HD-installed KNOPPIX system and I have also some other virtual machines ( ex. windows adv server ), and guess what : the wheel-mouse does not work under windows also !
So this brings me that is a vmware problem.

Maybe out of topic : has anybody yet found out how to use the wheelmouse under vmsware wkst ??

Thanks again.

Bobke