Non sense relationship error

[harrinho]

Hi Everyone, 

I'm trying to create the relationship below, which is actually a relationship that exists in the master dashboard and works fine but I get this error which I really don't see the reason. The other relationships that I have created are copied exactly from the master d/b and should work fine. 

Any ideas, where should I look at?

Many thanks for your thoughts 

[Greg_Deckler]

What error?

[harrinho]

So sorry, I forgot the attachement 😛

[Greg_Deckler]

OK, so I am assuming that your "WEEK PERIOD" table has unique values then?