Michelle, I had the same issue with my old and new FN shelves falling down two times. It was very scary, but everyone was ok. At first I thought maybe I had not put the shelves in the hook far enough, but that was not the case. Now we get wire and wrap it around the loop that is on the bottom of the shelf, and then we secured it to the side of the cage. Now it cannot move (we have tried!) It is a pain when you have to un-twist all the wires to get the shelves off and wash the shelf covers, but the babies are worth it! Dooks, Lori Olson [Posted in FML 6870]