Mr. Rost, I had a problem with "Referential Integrity" not working. Expert 8 Lesson 5 TIME INDEX 11:30. I reviewed all of the previous lessons from lesson 2. What I finally came up with was that the default values in any number field, i.e. foreign Key Fields, except the Main Key field have to have a default value set to 0 (zero). Not sure if you cover this or not in any previous lessons or not. If you did then I missed it and apologize for bringing it up.