My son had this problem at his front door (all glass). nothing seemed to work until he printed a picture of an owl and taped it to the window. that solved the problem. earlier this year, he had a different bird land on the edge of the door frame and "knock" on the window. I know it wasn't funny because it drove my son crazy but it was funny. he just leaned a big piece of cardboard he had handy at the door and it stopped. Crazy birds!!