This may be because your bed is out of square. Remove the mattress, put something that you know is square (even a piece of copy paper) in the corner of the bed. If the side and end of the bed don't line up with the edges of the paper, it is out of square. Gently lift the corner of the bed and shift it to create a 90 degree angle. Email our customer service department at info@prepacmfg.com for more detailed instructions.