I think I know what you are talking about. We tried ours (same 5er) last weekend and if you sit in the middle to get into the bed the unit folds. I noticed both the legs sliding out (away from the bed not folding) and the head of the bed rising. As long as we did not sit in the middle and were laying down it was fine. I would also like to know if there is some sort of lock in the middle I am missing.