Looking to take a .sav file and put it in my ez flash jr

I’m trying to transfer an old .SAV file to my EZ flash junior so that I can trade my Pokémon from Pokémon crystal but I can’t get the file to properly run and it doesn’t overwrite my previous save. Does anyone have any idea how I can fix this? I’ve tried overwriting the save file twice and both times it just replaced the file with a pre-existing one instead of the file which has all my Pokémon.