Thanks, the problem is solved. I mixed up a path in Vbulletin with the sub-domain of my provider, which also sends a index.php. So some scripts, which send a index.php theirselfes produced "index.php/index.php" and didn't work.
May I add another question?
I added Photopost on my site http://forum.sagen.at
and would like to have those 6 lines in German language:
Individual user galleries - any photo category
Photos of a particular subject