Problem with umlaute in usernames form active directory while changing rights

Ldap authenticated usernames containing umlaute can not get rights [solved: nor added to another group than XWikiAllGroup.]
Either an empty object is created in the group or if the object was created, the table of the group can not be seen in the webinterface and the error describes: the environment prevents table to load data (i hope its correct translated in german its called "Die Umgebung verhindert, dass die Tabelle Daten laden kann.") and the user cant deleted from the group without using XEclipse.