I had the exact same problem. My solution was - a nice 80 degree basking spot.
I had my geckos at room temp - fine for all around living - but in Minnesota, for some reason - the lower 70's weren't conducive to breeding. I have a hot spot of 80 on the top of a branch, and my main temp is in 75-78 (although I have spots on the bottom which are lower).
As soon as I raised the temps (this summer, in fact) - I started getting egg production. Interesting, huh?
I can't promise that this is your solution - but it was to me. Just make sure it doesn't get too high - too much heat is not good for them either.
Hope this helps or gives you some ideas.
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Monte Meyer
Powergeckos
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