I agree with the others that have posted above on the warmer basking temps, but make sure you supply a gradient across the cage floor. A warmer basking spot is needed for proper embryo development, however a cooler area will be needed for female ovulation and proper spermatozoa development with the male. If the entire cage substrate is close to 90 or above you will end up sterilizing the male, or kill sperm within the female after copulation. The gradient for this species should typically run from 80 at one end of the cage to 90 to 95 at the warm end during breeding trials. Your cooling them to 60 for a couple of months was good and will definitely increase your chances of success.

Kelly