I had a similar problem to this because every time I tried saving to NOR it'd tell me there's not enough space on the NOR. Here's how you fix it.
Take your sd card, plug it into the computer, delete the rom and sav file on the sd card (The one that you're trying to put in NOR), then get the original copy of that same rom and re-install it onto your sd card (Using EZ4 Client or whatever you have). Plug the sd card into the EZ4, then put the EZ4 back into your gameboy, and now it should work when you press select on the rom when you send it to NOR. (Atleast it did for me) Hope this helps.
Take your sd card, plug it into the computer, delete the rom and sav file on the sd card (The one that you're trying to put in NOR), then get the original copy of that same rom and re-install it onto your sd card (Using EZ4 Client or whatever you have). Plug the sd card into the EZ4, then put the EZ4 back into your gameboy, and now it should work when you press select on the rom when you send it to NOR. (Atleast it did for me) Hope this helps.