it helped :) my problem was the update, we forgot to update conf/dokuwiki.php. It was little bit of work after realising that you may not make changes to dokuwiki.php but to overwrite the $conf-Values in local.php. Thanks for your pointer to the thread.
If someone else encounters this problem, read carefully
http://wiki.splitbrain.org/wiki:faq:toolbar, especially point 3, this helped me.