The "Referential Integrity" is greyed out using your downloaded file Access-2010-X1.zip once I created the join "0217-02:50).

Any, I had to delete the new Record and play a few time and it finally works.  Had to close the Access file and going back in again. I'm just not sure of what happened? Just wanted to let you know about Joni Moore's comment (top of the page) is true though.

This is the same thing that Joni stated on the first topic of this video:

"Joni Moore on 9/18/2013: What if the "Referential Integrity" box is not available to check (it's greyed out)? What would cause that?"