I have 2 mallard eggs that should be hatching any day. One egg is completely dark and the air sack is very large, but no piping, no sound. Other egg 1/2 dark blodd vessels look strange no movement, air sack has only grown a small amount. Are they dead? Some advice is needed. My incubator does not tell me the humidity. I just keep water in the tray. Temp it at 36.6 c.