The problem is usually that the wide fabric strap is folding and getting cought under the lid. Watch it closely when you close the lid and make sure the strap bows toward the inside of the bag. Your lid will probably latch then. At least that is what happens to mine frequently.
Thanks for the advice. I searched the forum and found the fabric problem and I found out about the little fingers. I went out and checked and sure enough the fabric has the crease in it and was getting caught. Fixed that and then it still was a little loose bent the fingers a little bit and problem solved. Thanks for the help