Why does Humanoid.Strafing do nothing?

I assumed that this event would fire when the player was in first person or mouselock and pressed A or D etc to strafe to the left and right. However when I went to test this it did absolutely nothing. My code is not wrong so why isn't this firing?

My code and yes it is in a local script.

local Player = game.Players.LocalPlayer
Chara = Player.Character
Humanoid = Chara.Humanoid
Humanoid.Strafing:connect(function()
    print("Strafing")
end)