Chicks usually hatch after 21 days of incubation but it is not unusual for the chicks to do so after 22, 23 or even 24 days so when nothing hatched after 21 day I still waited ... waited until day 24 and decided to open one egg and see what is going on. I first candled the eggs to see if there are movements in the eggs, but saw none. Opening one after another it was clear that somewhere along the line the chicks died premature since the egg yolk is still very much visible. I can't pinpoint what the issue was; bacterial infection maybe? I don't know. They sure developed very nice and then something happened which killed them. Mystery.I started this incubation with 14 eggs of which 7 weren't fertilized. 1 was a quitter in the early days and 7 were growing well ... it seemed at that time. Sad really ... Not sure what to do if Im to incubate once again ... since I dont know what the issue was how do I fix it?