udf can't read superblock

[moormaster]

Binary package hint: udftools

I am using following DVD burner:
    LG-H42L

Whenever I try to mount a DVD-RAM with packet-writing:
    mount -o defaults,noauto,user -t udf /dev/pktcdvd/dvdram0 /mnt

...i get following error:
    mount: /dev/pktcdvd/dvdram0: can't read superblock

The DVD is formatted with udf and can be successfully mounted for read/write without using packetwrite.
dmesg also shows an interesting entry every time i try to mount the packetwriting-device:

    [ 6471.784327] pktcdvd: pktcdvd0 couldn't set write speed
    [ 6472.189717] pktcdvd: write speed 0kB/s
    [ 6472.191620] pktcdvd: bb 00 00 00 00 00 00 00 00 00 00 00 - sense 00.35.00 (No sense)

The /etc/default/udftools file looks basically like this:
    DEVICES="/dev/sr0"
    NEWINTNAMES="dvdram0 dvdram1 dvdram2 dvdram3"