I have 2-Rhode Island and 2-Black Sexlink. Got them as chicks this spring. 3 out of the 4 have been laying eggs for almost a month. The one Black sexlink is not laying. She did lay one egg but it was like a membrane(not a solid egg). She is the biggest of the hens and has not done anything since then. I have the hens in my backyard in a coop. Not free range. Any ideas to help her start laying or do they sometimes just don't lay.