Why are skinks so damn difficult to breed?

I believe I do everything correctly, the setup, the food, the temp, and the humidity...the sixteen skinks I got still refuse to copulate.<br><br>They all act matey around each other, so I don't think they don't like each other.<br><br>I'm going insane because I've wasted so much money on these things and none of them will even get close to mating.<br><br>Wtf is going on? Why are you such complicated creatures? Can someone tell me what I'm doing wrong.<br><br>I've had them for 2 years now. I honestly can't understand it, no matter how many articles and pages I read.<br><br>Any help?