I have just had one put in this morning and they seem to be OK with leaving the house through it but don't seem to 'get' how to get back in. I've done this so that I don't have to keep letting them in / out and also so we can go out for the day without worrying about them but one is still sitting at the door where he can see us (not the catflap door) waiting to be let in. Do I leave him out until he works out he has to use the catflap if he wants to get fed??