problems burning multi session dvd-rw

[Timothy Smith]

i'm having some troubles burning a multi session dvd-rw. i blanked te 
dvd to make sure it was in sequential mode

%dvd+rw-format /dev/cd0a -blank
* DVD\uffffRW format utility by <appro at fy.chalmers.se>, version 4.9.
* 4.7GB DVD-RW media in Sequential mode detected.
* blanking 100.0|

i then burnt some files to it with

%growisofs -Z /dev/cd0a -r -J -speed=4 /home/timothy/burning/*

this burns the files sucessfully to the dvd.
now according to the docs i should be able to append another session to 
the dvd with the -M option. this is what i get

%growisofs -M /dev/cd0a -r -J -speed=4 /home/timothy/burning/*
:-( unable to pread64(2) primary volume descriptor: Invalid argument
    you most likely want to use -Z option.

i'm using 4.10 and an LG multiformat dvd burner.