Nintendo Famicom Bios issues

So I got a hold of the bios file to be able to play Nintendo Family Computer games with an NES emulator, but I'm having issues with it. I renamed it to disksys.rom like you are suppose to, placed it into the root folder of the emulator, and directed the file location for the FDS Bios rom, and yet when I try to play an FDS game like Super Mario Brothers 2 for example, I get an error message that on the lines it can't detect the bios file. What am I doing wrong? Also the emulator is FCEUX 2.2.2, and that I would like to know how to get it working also for the Nester J 0.51b emulator also please.