NEC CDR C251 on XP

Hi,
I have a CDR C251 which is a CD-ROM with Changer for 4 CDs. It takes 4 CDs
and you can play them as if you got 4 CD drives on your computer. I
installed it on my XP computer and it just won't work. All over the internet
I read that XP handles CD Changers, me XP recognizes the CD but it gives
only one Disk letter intead of 4 and the device won't work. Is there
anywhere where I can get some information about this. At NEC computers, no
way to getany answere. They just won't help you. I wander how they live. The
CD drive is supposed to be a classical simple drive. It's just this changer
that is going nuts.
Thanks for hour help
Greg