We are brand new to chickens as our town just passed an ordinance allowing us to have up to 6 hens (No roosters) in our back yards. WE have raised two sets of chicks so far, since February of this year. We have been raising chickens since February. We presently have two Cochin's, two Buff Orpingtons (all of these are around 20 weeks old -raised from chicks) and in the flock now are two 20 month old Black Australorp's who were introduced slowly over 8 weeks ago (they were introduced to the flock over a period of 2 weeks). One of them lays regularly (noisy britches) about 5 a week, but the other one does not lay at all and has not since we got her over 8 weeks ago. This is my question what is wrong with this hen? She eats and drinks fine, she is rather large (bigger than her sister) but is not bigger than she was when we got her. She was laying when we first got her, the 2nd day she laid from the roost and has not laid since. One of the Buff Orpingtons is ready to lay, her comb is bright red and she is doing the chicken laying dance. However the other one has pea comb just as do the Cochin's. They free roam every day in our 1/3 acre back yard surrounded by a brick fence (6-8 feet tall). The Coop is 8 feet wide, 6 foot long, and 6 foot high. Has three different roosts that are all connected by quite separate from each other in case they need space. They are always closed up at night and then let out in the morning. They get a combination of GMO / Organic layer crumbles - Organic grains (rolled oats, barley, Non-GMO corn (tiny bit right now), Black oil sunflower seeds, flax seed, cotton seed meal, and red millet) for scratch which they get every evening between 1/2 - 1 hour before bed time. They have a timer on the coop that stays on until midnight every day as the hours are getting shorter. The Black Australorps are definitely Alpha and Beta of the flock, now. They don't attack the other bird’s just stare them down every few minutes. I guess I should say we have three dogs and the youngest of the dogs is a chicken protector from any Cats that may enter the yard. We have taken steps to stop predators from coming into the yard, however those sneaky cats can jump the 10 foot fence. They have a large swimming pool full of fermenting food scraps and straw, it’s a large compost pile, which they can get into and scratch for all the wonderful bugs that think they are safe from predators in there. The bottom is open in some places so it drains also. The black Australorps came from a home with a fenced in (12'x24') run and a (15' x 15') coop for 25 hens. They have a smaller coop but less hens to share it with, there is no run because they free range on my yard. They also have both molted in the last 12 weeks. They were finishing their molt when we got them. But now they are great and all their feathers are back. For treats they get organic Romaine lettuce, Pomegranates, apples, hydroponic greens, watermelon, a wee bit of scratch (as described before) and of course their crumbles. I tried pellets but no one would eat them so we are left with crumbles. Sometimes they get freeze dried meal worms, but their absolute favorite is real live super worms. They are given these every two weeks or so. We also have grubs in our yard and they eat them regularly, almost everyday. Wondering if anyone has any idea why this one black Australorp is not laying? Why the 2nd Orpington is not developing as fast as her sister, she seems to be around 6 weeks delayed and am I doing something wrong? Thanks for reading and ask questions if you need more information.