Not breeding??

[Rebecca]

Has anyone come across a pair of crested geckos that just won't breed?? I tired seperating them, then putting them back together, first in his cage then in her cage. I've tried lowering temps, rasing the temps everything. And this is not just this year it was last year too. I know it's a male and female, you can tell by the bulge and lack of bulge. I've kinda just givien up and just put them together. I plan on getting another male/female and try breeing agian. I was just wondering if any one has come across this before?? Or maybe there is something else I could try??