Thanks for you help !
But unfortunatly, it doesn't work, I've used a Delcatty and a Togetic. They both are in the "fairy" egg group, so it should work, but even after 3 days in the daycare, nothing happened, is it normal ?
By the way, I bought the pokemons, could that be the problem ?
I'll try with a Pikachu, to see if it works.
Edit : It still doesn't work
Edit 2 : I finally found the problem ! There are two persons in the day care, one is for leveling and the other for breeding, I was talking to the leveling one ahah