I just bought some nesting boxes for my 5 hens and they will not lay in it! We tried golf balls, putting their eggs in there after they are layed, and even putting them in there for half an hour with some eggs to try to give them the hint, Yet they still lay in the corner of their coop! Why? They can get up there because they do and the vet said it was a perfect height and good location but it still doesn't have a single egg layed there! How do I convince them to lay there?