vdr-plugin-burn

when i try to burn an ISO-image, it fails with the following error in dvd.log

[vdr] writing detail log to /tmp/vdr-burn.45_minuuttia.qLltZL/dvd.log
[vdr] starting sh -c 'vdrburn-dvd.sh render' (pid = 11781)
...
...
...
[demux] 100 %
[demux] 101 %audio frames: wri/pre/skip/ins/add 109050/0/0/0/0 @ 00:43:37.200 done...
[demux] ---> new File: '/tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/vdrsync.mpa'
[demux] 
[demux] summary of created media files:
[demux] .Video (m2v):    65430 Frames    00:43:37.200        '/tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/vdrsync.mpv'
[demux] Audio 0 (mp2):    109050 Frames    00:43:37.200    0/0/0/0    '/tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/vdrsync.mpa'
[demux] => 1 030 087 384 bytes written...
[demux] -> we have 7 warnings/errors.
[demux] done...    1 collection(s) processed  @ 00:00:39.718
[demux]  
[demux] + exit 0
[vdr] process demux (pid = 11807) exited gracefully (exit code 0)
[vdr] process "demux" exited
[vdr] starting sh -c 'vdrburn-dvd.sh mplex' (pid = 11835)
[mplex] + set -e
[mplex] + unset SUDO_COMMAND
[mplex] + echo 'Script invokation: mplex'
[mplex] Script invokation: mplex
[mplex] ++ which ionice
[mplex] ++ echo 'ionice -c 3'
[mplex] + IO_NICE='ionice -c 3'
[mplex] + case $1 in
[mplex] + MPLEX_OPTS='-S 0'
[mplex] + mplex -h
[mplex] + grep -q -- --ignore-seqend-markers
[mplex] + MPLEX_OPTS='-S 0 -M'
[mplex] + ionice -c 3 mplex -f 8 -S 0 -M -o /tmp/vdr-burn.45_minuuttia.xpvoKw/VDRSYNC.0/movie.mpg /tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/vdrsync.mpv /tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/
[mplex]    INFO: [mplex] mplex version 1.9.0 (2.2.7 $Date: 2006/02/01 22:23:01 $)
[mplex] **ERROR: [mplex] Unable to read from /tmp/vdr-burn.45_minuuttia.qLltZL/VDRSYNC.0/.
[vdr] process mplex (pid = 11835) exited gracefully (exit code 1)
[vdr] process "mplex" exited
[vdr] ERROR: process author (pid = 11808) crashed (signal 15)

Running Ubuntu 12.04 LTS, vdr 2.0 and burn-0.2.2