Hi,
Two years is the earliest a pair should be set up for breeding, so the hens may be too young. And even if they are old enough it can be inexperience. First clutches almost always fail no matter what. But if you didn’t rest your pair for 6 months after the infertile clutch, then they are probably too run down right now to be nesting again. Once they are done with these eggs, go ahead and remove the est box and rest the pair for 6 months, and then they can try again. You should only allow 2 clutches per year, with the 6 month rest in between. In the wild they only nest once a year. In captivity, they will literally keep laying eggs until the hen dies because they do not get the environmental signs to take a break. So it’s up to you to make your pairs rest after each clutch, whether they hatch or not.
Thank you for asking Lafeber,
Brenda