Ok, in one easy bundle, some questions, and suggestions:
Questions
Size of their tank?
Their size?
Tank temp?
Some Suggestions
Raise the temp to 79-81F
Do a large water change (~60%) with slightly warmer water (or colder, I hear they both work fine)
Feeding flakes and pellets will condition the female, but I'd suggest maybe 3 days of frozen or live food, and that almost immediately brings my female into breeding mode
If there's a cave in the tank, good. If not, add one. A flower pot, rock arrangement, large PVC pipe, whatever. If they can go inside and stay inside, you're good.