USB CD/DVD Burner

[eric tanguy]

When i hotplug my plextor cd/dvd burner i can't mount it. When I look to
dmesg i can see this :
usb 1-4: new high speed USB device using address 4
scsi1 : SCSI emulation for USB Mass Storage devices
  Vendor: PLEXTOR   Model: DVDR   PX-708A    Rev: 1.06
  Type:   CD-ROM                             ANSI SCSI revision: 02
USB Mass Storage device found at 4
sr0: scsi3-mmc drive: 40x/40x writer cd/rw xa/form2 cdda tray
Attached scsi CD-ROM sr0 at scsi1, channel 0, id 0, lun 0

but when i try to mount with a cdrom in it:
mount /dev/sr0 /mnt/archos
mount: périphérique spécial /dev/sr0 n'existe pas

When i try to use k3b to erase a cdrw (for example), k3b see the burner
but after i have an error 255 from cdrecord.
I can't see what will be the problem because it worked fine with FC1.
Thanxes