I have a silkie hen on a clutch of 5. Yesterday was day 21. At 11pm i checked three of them in which two seemed to not have anything (stoped growing/dead) and the third was chirping from inside. Now i read that if they are chirping then it means they broke into the air sac. Ive noticed this at 11pm and its now 10am so its been almost 12hrs and theres no external pip yet .... is this normal???