egg cracking in incubation
 

one of my fertile Horsfield's egg's has got a crack in it, why has it done this? what am i doing wrong? they are on day 17 into incubation, this happened in my last clutch, and i put clear nail varnish over it, and the baby grew and hatched,

Cracks usually happen because the incubation medium is to wet Kev.

Danny