Hey twixx! This happens to me all the time. Basically, it is a small internal piece. Spread each side apart, and shine a light inside (like a flashight or something), and look for a small piece in the center that looks like it has come out a bit. Then, shove your finger into it and try to pop it back in. It will hurt, but you'll hear a satisfying snap when it goes back in. If it isn't working well, try turning the layer best you can to 45 degrees with the other one. Cheers!