I worked now. The German WP version is damaged. I tried the original English version and – boom – it worked. As simple as usual. Now I have to think on getting the German language into the installation without loosing half of the features 😀
i actually did that. but it is still not able to show importers.
maybe there’s a manual way? or can you say which files are missing? maybe I can get them from somewhere else
edit: I re-upload the wp-files 2 third time, now. I don’t believe that it will change anything.