Thanks, for your fast respond! Unfortunately it doesn’t work. But I could fix it by myself with trying.
With poEdit the words were translatet but when I opened the file with CodeStyling Localization and searched for the “</span>” – tag I found message, notification, friends and groups twice:
Once translatet to German and once not. I translatet all to German who were not translatet and it worked. I have no idea why this was that way but now I’m happy.
I sent the file also to deckerweb and a topic in German WordPress so the other user with this issue can use the file.