User-Synchronisation Ubuntu Client

I have the following Problem:
I connected an Ubuntu Client to a UCS-Domain via the ucs-domain-join Skript. The Ubuntu-Client joined the Domain successfully. But when I then create a new User in the UCS-Domain and restart the Ubuntu-Client, I cant log in as the new created User. However I still can login as one of the users, that were already created when I joined the Domain.

Thank you for the feedback.
Max