usbd.conf not mounting usb mass storage

[Vittorio]

 Under FreeBSD 5.4 In my laptop I have the following item in usbd.conf to  
mount a usb-mass storage:

device "SWISSBIT"
        vendor  0x1370
        product 0x2168
        devname "umass0"
        attach "/sbin/mount_msdosfs /dev/da0 /mnt/swissbit"


When I insert the device this are the messages:


fbsd# usbd -v -d
usbd: opened /dev/usb0
usbd: opened /dev/usb1
usbd: reading configuration file /etc/usbd.conf
usbd: opened /dev/usb
usbd: device-attach event at 1114704239.430921000, Twist, SWISSBIT:
  vndr=0x1370 prdct=0x2168 rlse=0x0200 clss=0x0000 subclss=0x0000 prtcl=0x0000
  device names: umass0
usbd: Found action 'SWISSBIT' for Twist, SWISSBIT at umass0
usbd: Executing '/sbin/mount_msdosfs /dev/da0 /mnt/swissbit'
mount_msdosfs: /dev/da0: No such file or directory
usbd: '/sbin/mount_msdosfs /dev/da0 /mnt/swissbit' returned 71


While giving the same command by hand in a root console 
'/sbin/mount_msdosfs /dev/da0 /mnt/swissbit' it all goes smooth and I find 
the share mounted.

Where am I wrong?
Vittorio