1:n relation does not validate

   In my entity model I defined a 1:n definition between Person and DocumentA person can have many documents and each document belongs to one person.

I try to test it with the following test:

        [TestMethod]
        [ExpectedException(typeof(Exception))]
        public void SaveDocumentWithoutPerson

        {
            Dokument newDokument= new Dokument();
            newDokument.Id = System.Guid.NewGuid();
            // set dokument properties
            newDokument.ErfasstAm = DateTime.Now;
            newDokument.MutiertAm = DateTime.Now;

            Manager.AddEntity(newDokument);    // I expected that this would throw an exception
            Manager.SaveChanges();
        }

It does not throw an exception and the document without the person ends up in the database!
How is that possible?

Here the properties of the association  (Person is called MasterEntity)

()