Try to get both of them engaged and locked at the same time. Also, the rear on the left side of my bike was pushed out, I used a pair of channel lock pliers to bend it back strait and after I got it to lock down again it was okay.
Better to be hated for who you are, then loved for someone you are not.
Sometimes the bottom rubber mount bumpers are not set on the bottom of the bag are not lined up with the tube rail support not allowing the Bail Head Pins to line up with the frame mount clips. Be sure the bag is completely seated and in the right spot front to back.