I received 12 20-22week old red sex link pullets in early september and put them with 5 older hens. They free range during the day and are cooped up at night. All the chickens get along and seem very happy. I have not gotten any eggs from the pullets yet. My older hens are laying, just none from the new ones. I use good quality laying mash, oyster shell is also out, and scratch. Any ideas what to do?