I started incubating 12 cochin bantam eggs 3 weeks ago on day 19 1 hatched and died shortly after due to getting is head stuck in a small hole in the tray that the eggs were sitting on. later that night 2 more hatched and another 3 in the day. 3 eggs were not fertile so i was expecting 9 chicks 8 after one died but 3 have not hatched and i have 5 that have. Any idea why?