Muscovy Ducks Day 38 and not hatching or showing signs

[Liszis90]

First time hatching Muscovy Duck eggs and they seem to be showing no signs of hatching... 1 has developed a really dark part of the egg shell and im worried they may all be dead. I've candled them and attached photos for your opinion. I really have no idea, I thought i'd done everything correct HELP!

 

[Pyxis]

What was your temperature throughout incubation, and did you confirm it with a calibrated thermometer? Is your incubator still air or forced air? Lastly, what humidity did you use throughout incubation?