Our youngest girls are 19 weeks old now. One of the Black Australorp's went into the nesting box, made herself cozy for a while and in about 30 minutes she was standing up and singing at the top of her lungs. Our EE went into the coop and joined her for a duet. I was so excited! But once the BA jumped out of the box I looked inside and there wasn't any egg. No egg anywhere, not even a tiny one...not in the box, not in the coop, no egg to be found. I haven't had this happen before (we've only been raising chickens since last December). Is this normal? I watched her for some time later and she doesn't act like she's egg bound (we have had that before with an older chicken so seen that). What's up?