I was very careful.Make sure that you selected the right League of Legends.exe like in the description of this thread.
I also did a full repair and tried again but it still doesn't work.
Maybe they did a hotfix ? I don't know.
Thanks for the quick andswer tho
C:\League of Legends\RADS\solutions\lol_game_client_sln\release s\0.0.1.180\deploy\League of Legends.exe
EDIT : it worked after a reboot for some reasons