Do you know whats the problem with my pairs???

[Saeid008]

please read the text below.
for 5 month ago I select 3 pair of pigeon discus,
all of them, produce baby but for ex. 1 or 2,
so I am certainly there are male and female in each pair.
please suppose 3 pairs are: A, B, C,
Pair A, for first time produce 1 baby and after that for along time their egg change to white.
pair B, for many times they cant produce any baby so I decided to separate the PVC after spawning, in this time, the eggs hatched in artificial way (10-20 baby), But for next time again their eggs change to white.
Pair C, for this pair i separated PVC and produce many baby. But next time when they put eggs I was in the room and I saw the male did not work, and the eggs change to white.
I tiered and asked some person, Finally I separate all pairs to 2 tank, one of them include only male and another one include only female for 2 month.
after that I put all the male and female in same tank.
Now I separate 2 pair, But I have same problem as I said.
my male did not work well again.
I know certainly that the water parameter is well. actually I can measured TDS ant it was between 60-100. temperature is between 27-29.
what should I do??
could you please guide me?
tnx

[Keith Perkins]

You could try putting a divider in the pairs tanks or putting them in adjacent tanks for a few weeks so they can see each other but can't get together to spawn. This may cause the males interest to increase so he spawns better. Also putting another male in a tank adjacent to a pair sometimes has the same affect. Best of luck with your efforts.

[Saeid008]

Thank you very much,
I should try this way.