Sorry, here is the screenshot of the relationship.
The relationship looks correct. So unless something is wrong with your layout (seems unlikely), I'd look at the value of ID fields in the records of each table. What you describe is what I would expect to see if every record in University and every record in Agreement all had exactly the same value in their respective ID fields. Given the extra "crows feet" that should not be there in your relationship graph, that's my first guess as to what is wrong.
University::ID should be defined to auto-enter either a serial number into a field of type number or the results of the auto-enter calculation: Get ( UUID ) into a text field.
I'm guessing here that this is not the case.
Thanks for the reply. The University ID was indeed not a serial number, but it was a unique number, which I thought would be fine. I couldn't get the problem solved by fixing my original database, but when building a new one, with just serial numbers in the ID-fields, it solved the problem. Thanks!