Ah okay I investigated it. If I haven't read wrong, obviously not everybody uses QWERTY keyboard, so some users don't use WASD because of the position of those keys. It's true that I mapped the controls to the Key Character insted of the Key Position. My bad, I didn't know about this problem.
I'll have it in mind next time I develop a WASD controller. Thanks for telling me!! Otherwise I wouldn't have known about this! :D