Same problem here too redchequer, bought in new stock 4 pair and two hen which I paired to my onw stock ,so the big plan was to pair them all up together 28 Dec and float the eggs from the stock birds under some of the widows , well first four eggs from the new stock (which are yearlings and a two year old hen) all blank and one off the other hens I brought in paired to my own cock her first egg broken ,the other got crushed in the nest expletive remove , Only let them sit 5-6 days so they laid again pretty quick and they all seem to be full this round ,fingers crossed .Can't explain it ,last year every egg hatched that was laid last year ,maybe is the weather or the section they were in wasn't the biggest so maybe not getting piece to do there business. Never known a year like this it's maybe a sign of things to come