Bark Bark Bark

Our dog Wall.E doesn't bark much at all. He is a very quiet calm dog. My parents have a bichon and she can be yippy. When left outside for any length of time she will stand by the door and bark. She won't quit either until someone comes to let her in. I'm not sure why she does that. At times it's so nice outside and she still wants to be indoors. Silly dog...........