I think what they were referring to was the friendship because it also didn't work for me when trying to get my Eevee to evolve into an Umbreon. It didn't evolve into a Sylveon either so it basically just did nothing. I haven't tried since the code came out though, it might have been fixed?
Trade it to someone and get that someone to trade it back to you and it should work as soon as you level up the pokemon.
You can also use a backup to trade with yourself via GTS.