One of Jazz and Grace's eggs hatched yesterday. I looked at the other eggs and it seems like they have dried out. This typically happens when the air is dry. The membrane on the inside of the egg can dry out, the egg shell also can dry out. This condition can cause the babies to die in the egg. Babies can also die as they try to breakout of the egg. Babies that hatch can also die shortly after hatching because of exhaustion.  The egg shell might be to hard for them to break through. The only thing you can do to prevent this from happening is to place a humidifier in the room that the birds are breeding in.