I usually only do pairs with all my Tincs and have success that way. I use the coco huts with the petri dish under it. I don't pay too much attention to them after that but I will say my Matechos are the least prolific off all my tincs. Don't ask me why. They are also my youngest pair so that may play a part in it. I have only pulled two babies from that tank over the last six months so I haven't been too successful with them either. My tanks are pretty over grown right now and there could be babies hiding and I wouldn't know it. I kind of just let my frogs be. I have an automated misting system that comes on for a few seconds 3-4 times a day. They put the tads in little puddles on the ground because I don't have bowls or any other place for them to put them. Again I kind of just let my frogs do their own thing and then pull babies when I spot them hopping around the tank. The age of your frogs is more likely the reason. 15 months old is still a little young for some tincs. If they hit the 2 year mark and aren't producing then I would start to worry. I also think I would separate out and just keep them in mated pairs. If you can figure out the sexes for certain then there are people that may be willing to trade with you for another female. That way you can have two pairs. That would probably be less stressful on the frogs and you might have more success.