I put 18 silverlace wing eggs, 6 light sussex, and 6 duck eggs in my incubator. The chickens were due to hatch 3rd aug by the 8th only 6 hatched so i opened the rest to see and they were all fully formed but dead and they still had the yoke sak out side of there body. What did i do wrong? I kept the 2 water troughs toped up with tepid water, on open it once a day. Only 1 out of the 6 ducks hatched an again the same thing all fully formed but dead? So disapointing. I was going to get some Ixworths next but after this desaster im very reluctant. Please advise. Many thanks