I set 6 saxony duck eggs in the incubator to hatch and only 3 started to develop. I stopped turning at day 28 and now it is day 31 and no pip. I thought they were suppose to hatch on day 28-30. I'm a nurse so I listened to the eggs with my stethoscope and heard heart beats in 2 out of the 3 eggs. Has anyone hatched this type of duck egg before and how long did it take them to hatch? Thanks!!!