You may have to request an LDAP app update for version 4.3.1 from Mendix
The sollution is Stephan's comment. I forgot to turn of the cloud security check.
I think this occurs because the ldap module is not completely translated. Allthough it has been a while since i last used it so i can be wrong there.
To check that simply go to your modeler and then to the language operations tab under tools and see if the dutch tab has as many entries as the english US tab.