Cynops cyanurus breeding???

I currently own 3.3 Fired Bellied Blue Tailed Newts (Cynops cyanurus). I have had them for about 2 years for 3 of them and about a year for the others. They are healthy, and well fed. The females look ready to breed, the males tails have recently turned much more blue and they too look ready but they do not breed.

I cannot figure out the trigger to get them to breed. I have tried same temp water changes, cool water changes and warmer water changes - none of that does anything from what I can tell. I have tried water changes as frequently as every day to mimic rain, no good came of it. I do water changes when it rains outside and that does not help either.

The tank has plants, duck weed and a fine leaved but brush like plant for which I cannot recall the name. I have that floating in the tank and it gives ample area in which to breed as it is pretty thick/abundant.

I feed them frozen worms, fresh cut up earthworms, carnivore pellets and live black worms. They are well fed.

Any help wpuld be greatly appreciated.

Thanks,
Glenn B