Thanks for all your hints. But it was something completely different. For testing MythTV 0.28 (unstable) and MythTV 0.27 (stable) I copied my MySQL database 'mythconverg' to two new databases 'mythconverg027' and 'mythconverg028'. But I forgot to change the database name 'mythconverg' in Apache's mythweb.conf. Greetings, Björn