I have 7 hens out of the 7 only 1 has been laying for the past two months. They are all healthy bug free and happy. I feed 16 % laying pellets with 3 grain scratch as a treat. Sometimes they get to free range. Hens range from ages from 1yr to 4yrs old. Only two are singing and one of those two is laying. All have beautiful nests and a dry place to go lay. They started laying the 1st week of april last year. Any advice would be great!