On Servers i can earn the Discipline, and i can use it even after relogging, the server saves this information, but removes the displaying on the Wizard-Workbench.

That isn't the problem, the fact that it removes the Displaying somehow removes also the limit.
(I set the Main Limit to 1 and the second limit to 2. as long as i stay ingame, i can only learn 1 main and 2 second disciplines. But if i relogg, i can again learn 2 second disciplines without remembering the limit that is set on the server. This way i can basicly learn all Magic-Types as second discipline, i just have to relogg...)

There are no Error-logs.