My Cats "Playing" Through The Door

So Mo and I have two cats, Cleveland and Turk. Cleveland is on this side of the door. We've had Turk for about a year and a half (Thanks Adopt-A-Cat) and the two still don't get along. I see them "playing" through the door and I think maybe they will be fine, but nope. Maybe I need to get a cat whisperer. - Sally