I have 4 Hens that were born on May 1. So they are 24 weeks old. 2 of the 4 have been laying but the other two have no played at all yet. I have 4 chickens and only one nesting box....... do you think I need to get a second box? Is this why they aren't laying? The 2 in the middle have been laying for weeks now! But the other 2 have not.