I have been very successful in breeding many different Types of Tortoise, but one that still frustrates me is the Russian Tortoise. I live in Southern Calif and have been lucky enough to have my Females lay eggs on a consistent basis, but they almost never hatch after incubating. Two males and three Females, mating behavior and egg laying every year. Incubation at 84- 86. Humidity Good. What am I missing?