CD recorder problem

[hubert.fauque@wanadoo.fr]

I have a CD recorder (Philips 2x2x6) and when I try
to write a CD with
   cdwrite -v -D /dev/sr0 cdimage.raw
I get
  cdwrite 2.0
  Track 01: data    7 Mb         
  opening scsi device: Read-only file system

At boot the CD recorder is detected:

Vendor: SCSI-CD   Model: ReWritable-2x2x6  Rev: 2.00
Type:   CD-ROM                    NSI SCSI revision: 02
Detected scsi CD-ROM sr0 at scsi0, channel 0, id 3, lun 0
(scsi0:0:3:0) Synchronous at 10.0 Mbyte/sec, offset 15.

I have changed the permissions of /dev/scd0 (to which sr0 is
symlinked) to 770; I get the same result;

I have surely missed something but what?
(I dont think it's a hardware problem because the recorder
works under Windows)

Thanks for any help
Hubert