udf cd rw

[Maupertuis Jean]

has somebody win to use cdrw with filesystem udf?
The cd is well formatted because i can use it under windows.
the unit under linux is scd0
first i try to mount it: mount -t udf /dev/scd0 /mnt
but it tell that /dev/scd0 is write protected
i chmod 0666 /dev/scd0 same result
i install (makedev) /dev/pktcdvd and try
pktsetup /dev/pktcdvd0 /dev/scd0
result:open packet device: No such device or address
I don't know what to do now

Jean