My hen has laid probably 50 eggs I've set and nearly all have been fertile and candle well. But they never peep or pip they just die in shell. I've had two, then one last week hatch successfully. Last night I had two peepers and one hatched. The other died half way out of shell (couldn't helped I was in the woods hunting).. now the survivor can't walk properly his right leg he holds up near his belly... lethal gene? Merak's?