Recently Milo has begun to scratch and meow at the door in my bedroom, particularly at night. Nothing changed to start this behavior, it just appeared one night! It is not a possible option to leave the door open, b/c the closet is also extra storage that won't fit elsewhere in the apartment and isn't safe for kitties. I cannot shut the bedroom door at night, b/c all three kitties sleep in there at some point of the night and Milo will then just scratch at the bedroom door until let it. Any suggestions of how to stop this scratching?