Late failure to hatch- what could be the reason?

[verlaj]

Of the shipped eggs I recently put under a broody, 4 looked developed at days 14 and 16. Three chicks hatched on time - the hen stayed on the nest for at least "full term" on the other egg, then I found her off the nest and the egg cold the following day. I took the egg and put it in an incubator, but gave up on it today, almost 48 hrs after it was due to hatch. I cracked it open - the chick appeared fully developed, just dead. So what could have gone wrong?

 

[heritagebirds]

I hatch in an incubator and had lost many late term chicks(Late quitters) due to too much humidity in the foam 'bator. I couldn't tell you under a hen. Hopefully someone else can help you out.

 

[verlaj]

After I retrieved the egg and moved it to the incubator, I had the humidity stabilized at about 64%. I haven't used an incubator before, but I thought that was about what it was supposed to be. Actually had a hard time getting it up to that level.