ERR: Cannot find button '9' as referenced by the subtitle

Hi,

I have a problem understanding what dvdauthor is trying to tell me. 

I try to mux from XML and get the messages:

INFO: dvdauthor creating VTS
STAT: Picking VTS 01

STAT: Processing //scratch/tmpdir_akte_x/tmpdir_akte_x_der_film_avi2mkv/empty.mpg...

INFO: Video pts = 0.133 .. 0.166
INFO: Audio[0] pts = 0.133 .. 1.157

STAT: Processing /scratch/tmpdir_akte_x/tmpdir_akte_x_der_film_avi2mkv/vtsm/vts_1_1.mpg...

INFO: Video pts = 0.133 .. 0.166
INFO: Audio[0] pts = 0.133 .. 1.157
INFO: Audio[32] pts = 0.133 .. 0.133

STAT: Processing /scratch/tmpdir_akte_x/tmpdir_akte_x_der_film_avi2mkv/vtsm/vts_1_audio.mpg...
ERR:  Cannot find button '9' as referenced by the subtitle
child exited with value 1

I don't understand. vts_1_audio.mpg has 8 buttons. And they are muxed as 8 buttons. 

Here are my recent files: 
http://dump.fangornsrealm.eu/vts_1_audio_spu.xml
http://dump.fangornsrealm.eu/dvdauthor.xml
http://dump.fangornsrealm.eu/vts_1_audio.mpg
http://dump.fangornsrealm.eu/vts_1_audiobg.ppm
http://dump.fangornsrealm.eu/vts_1_audio_hi.png
http://dump.fangornsrealm.eu/vts_1_audio_sel.png

http://dump.fangornsrealm.eu/vts_1_1.mpg
http://dump.fangornsrealm.eu/VTS_1.mpg
http://dump.fangornsrealm.eu/vts_1_subtitle.mpg

Can someone please clarify what is going wrong? I am seriously stuck. 

Thanks, 

Alexander Schwarzkopf

------------------------------------------------------------------------------
Everyone hates slow websites. So do we.
Make your web apps faster with AppDynamics
Download AppDynamics Lite for free today:
http://p.sf.net/sfu/appdyn_d2d_nov