Trouble with mounting USB stick as user

[Rob]

Hi all,

Got a small problem thats just driving me nuts. I have an MP3 player that 
appears as a memory stick - from dmesg:

umass0: iRiver Limited. iRiver Internet Audio Player IFP-700, rev 2.00/0.01, 
addr 2
da0 at umass-sim0 bus 0 target 0 lun 0
da0: <iriver MassStorage Disc > Removable Direct Access SCSI-0 device
da0: 1.000MB/s transfers
da0: 500MB (1024001 512 byte sectors: 64H 32S/T 500C)
(da0:umass-sim0:0:0:0): Synchronize cache failed, status == 0x10, scsi status 
== 0x0
(da0:umass-sim0:0:0:0): Synchronize cache failed, status == 0x10, scsi status 
== 0x0
(da0:umass-sim0:0:0:0): Synchronize cache failed, status == 0x10, scsi status 
== 0x0

The mount-point is owned by root:operator, and my user is a member of the 
operator group.  I have vfs.usermount=1 in sysctl.conf.  I have a devfs.rules 
file:

[riff_usb=10]
# Make USB drives readable to those in the "operator" group
add path 'da*' mode 0660 group operator

and it is referenced in rc.conf.

But ..

loop at riff ~ % mount /flash
mount_msdosfs: /dev/da0: Operation not permitted
loop at riff ~ % ls -la /dev/da0
crw-rw----  1 root  operator    0, 122 Feb  8 22:24 /dev/da0

Can anyone shed some light on what is happening here?

Cheers,
rob