Im useing the 5.25 drive bays I have two x LG blue ray burner optical drives in and two times Icy Box hot swap removable HDD cadies (IB-138SK-B-2 Black) They are sat imediatly above the small removable drive holder/box.
There locking it but with a slight tap become unlocked (the button still in locked position) There very difficult to get to lock as well have to keep trying over and over till they do lock in position. Its not just me my parts have gone of to a profesional comp chap to finish the build and he phoned me and is having the same problem