I think that the label can be written only if the user has the permission to write directly on the block device and this isn't done by default. If with "rw access to the drive" you mean rw access to the mountpoint I think it is the cause of the problem.
-- Usability: cannot change volume names https://launchpad.net/bugs/61966 -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
