Relationship between multiple columns in one table and one column in a lookup table

Hi,

I'm very new to PowerBI so this question may be too easy, but I hope someone can help me with it anyway:

I have one table with 3 columns: CaseNumber, OwnerID and CreatedByID.
I also have another table with 2 columns: UserID and FullName.

Now, I want to present two graphs: one showing the number of cases by owner and another showing the number of cases by creator. However, since the OwnerID and CreatedByID only show computer-generated numbers, I need to find the names of the owners/creators in the second table. To do this, I've created a relationship between OwnerID and UserID, as well as between CreatedByID and UserID.

Logically, when I try to create my bar chart based on this structure, PowerBI always uses the OwnerID-UserID relationship when I add FullName as a field. This makes it impossible for me to display the number of cases by creator.

Obviously I'm not using the relationships right, what can I do to fix this?

Thanks in advance!

Nina