Hatching puzzle I could use some help with.Today is day 21. Half the eggs in my incubator are mine and 1/2 a friends. Hers hatched out easy and started at day 20. All in brooder now. Mine are still working at it very slowly. I just have pipping in 5 of 6 chicks and it has taken all day, and now one chick starting to work its way out. All my eggs pipped in the middle away from the air space and none of hers did? Hers all at the correct end. No real difference in egg size or age of eggs. I have never had all pip in the wrong areas. I am giving mine the night to see if they can hatch on their own as they do not seem to be in distress at all and have air holes except for the unpipped one. I am just leaving the unpipped egg alone as I would have no idea of how to help with no pipping. Does anyone know what the problem with my eggs might be? The only thing I can think of is that my shells are much harder and hers were more breakable. I am wondering if it is a diet issue of some kind. Could the hard shells be the problem. Does it explain all pipping in the middle ? All of the eggs were turned the same and I have circulated air so it shouldn't be the temperature or any other variable I can think of? I am really baffled and would like to know how to not have this happen again.