Click on navigation (parent page) change label to "document tree"

Hi,
i got a new installation of XWiki Enterprise 8.3-milestone-2.

I try to descripe all i've done:

After installation, i set up xwiki for 3 languages (german, english and france). I am using the defaultskin, changed colortheme to cerulean, replaced the logo of xwiki to our logo with an jpg.

Then i went to home page of xwiki, renamed it and start writing subpages for it.

Problem: If i am clicking on an item in navigation, the clicked item(page) changes label to "document tree". If i am clicking on another subpage in navigation, this changes the label too. The pastclicked item will get his label back. So just the selected page in navigation changes the label.