Do you use breezy? If so, do you have the latest pmount from breezy-updates installed?
dpkg -s pmount | grep Version
should print 0.9.5-0ubuntu6 for Breezy.
** Changed in: gnome-volume-manager (Ubuntu)
Status: Unconfirmed => Needs Info
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no reaction on DVD-RAM
https://launchpad.net/malone/bugs/37907