FreeBSD 6.1RC1 AMD64 and Microsoft Mouse

[Sergio Mangialardi]

Hi,
I'm trying to use the Microsoft "Wireless Notebook Laser Mouse 6000"
(http://www.microsoft.com/hardware/mouseandkeyboard/productdetails.aspx?pid=048) 

I recently acquired, on my FreeBSD 6.1RC1 AMD64 laptop but the system
didn't recognize it, no /dev/ums0 device is created.
I've device usb and device ums statically compiled in the kernel, this
is the output of usbdevs -vd:

Controller /dev/usb0:
addr 1: full speed, self powered, config 1, UHCI root hub(0x0000),
VIA(0x0000), rev 1.00
   uhub0
  port 1 addr 2: low speed, power 100 mA, config 1, Microsoft Wireless
Optical Mouse® 1.00(0x00e1), Microsoft(0x045e), rev 0.07
  port 2 powered
Controller /dev/usb1:
addr 1: full speed, self powered, config 1, UHCI root hub(0x0000),
VIA(0x0000), rev 1.00
   uhub1
  port 1 powered
  port 2 powered
Controller /dev/usb2:
addr 1: full speed, self powered, config 1, UHCI root hub(0x0000),
VIA(0x0000), rev 1.00
   uhub2
  port 1 powered
  port 2 powered

Any ideas?
Thanks in advance

Sergio