My light sussex off e-bay are in the bator on day 10- some are good- but some -that are developing have a lot of "air space" in them- I can see where the chick is developing, but almost half the egg is empty. My eggs are as far along and in the same bator but they only have a small space at the top. Do you think they will make it with all that space? and why did this happen? Old eggs?