S.J.
When you snap it do you hear the snap or feel it? Sometimes I have to push mine pretty hard together to get them to snap. I have an evenflo too. If it snaps together and is somehow pulling apart it may be defective. Try snapping it and then pulling it apart without pushing the tabs in. It shouldn't come apart, if it does it's defective. There are a few car seat check places this weekend if your in the buffalo area. You could have one of them check it out. The schedule is on wgrz.com. Good luck. Hope this helped.
S.