What is the water quality like (ammonia, nitrite, nitrate, pH and GH) in numbers?
How long have the tanks been set up for?
What is the water temperature? You want the temperature around 26-28C.
How often do you do water changes and how much do you change?
How often do you feed them and what do you feed them?
How deep (high) is the water?
If the water is too deep or there is too much surface turbulence, they won't build a nest.
You need a picture on the back of the tank and some more floating plants. Water Sprite (Ceratopteris thalictroides/ cornuta) is the best floating plant for them. It can also be planted in the gravel.
If you are trying to breed fish, you should feed them 3-5 times per day for several weeks before breeding them. Use dry, frozen (but defrosted) and live foods. Raw or cooked prawn/ shrimp is one of the better foods for conditioning them. Buy some frozen prawn from a bait shop or supermarket and keep them in the freezer. Take one prawn out and remove the head, shell and gut (thin black tube in body) and throw these bits away. Use a pair of scissors to cut the remaining prawn tail into small bite size pieces and offer a few bits at a time. When the fish are full, stop feeding and remove uneaten food.
Frozen bloodworms and brineshrimp are also good. Live mozzie larvae are good too.
Do a 75% water change and gravel clean the substrate every day or two when feeding more often to make sure the water stays clean.
Put a cover over the tank so it covers most of the tank, to increase humidity and make the air warmer.
The following link has information on preparing food for baby fish. You need to get the fry food ready before you breed fish because most of the cultures take a month or more to get going.
https://www.fishforums.net/threads/back-to-basics-when-breeding-fish.448304/