It is actually quite rare that a single pair will mate. RETF's need competition and breeders usualy have about 2-3 males per female. The leaves will also need to be able to support 2-3 adult frogs as they perform their breeding rituals on the bottom of leaves (Sometimes a 3rd wheel will try and take over haha) Also you will need to have the rain system on for a few hours each night but im sure you already have that covered.
I have herd that they can be difficult to get breeding, but im sure with the mood set correctly it should be a huge difficulty.
I honestly have no clue what to do if a successful breeding actually occurs though so it would be a good idea to do some more research. How long to let the eggs stick to the leaf bottom or to let them drop into the water, what to feed the tads, what water temperatures to keep are all questions that would help your success.
Good luck
