Is there a trick to locking boards together? Boards are not going together very well for us and won't lay flat.

Unfortunately, there's no special trick that we can recommend. We know installations can be hard, so we recommend reviewing the installation guide. Also, make sure the tongue is going into the groove, as opposed to the other way around. This is a common problem. There's also an optional tapping method in the installation guide you might want to review. I hope that helps so you can get to enjoying your floor. - Chris