NAD remotes are a bit tricky to learn for all
universal remotes
I have tried several learning remotes (marantz,oneforall.etc.)with the same result as you have..

NAD say´s that the problem is that the original remote send´s a "wake up" signal before it begin to transmit.

You could try to hold the NAD remote away from the learningremote push the button you want to learn, then after a moment point it to the remote.