I'm betting that you're not hitting them at the right time of year. Males (in my little experience) seem to not want to continuously breed. Mine tend to get back to breeding after they have had a month or so break. Females will build follicles at all times of the year.

I don't bother with cooling or cycling temps for mine, either. I would suggest you just keep the females well fed and watch for building behavior. When they start bowl wrapping, introduce the male. Try the 4 days on, 6 days off. Watch for the bowl wrapping; pigging out; cool seeking; scenting; tail wagging; etc...then pair them. Pairing them before any follicle growth just tends to lead to frustration.

Good luck!