Filtering with slicer doesn't work - Table is not filtered

Hi,

I have following tables and relationships

So I have some workers ( Mitarbeiter) and they are working in some areas ( Organisationseinheit) . I want to filter workers by area. But when I choose Area oe1 , the table is not filtered ,and it should show only workers with id u1 and u2.  

Any advice why is this not working ,and how can I fix it ?

Thanks.