Punching-Script, saying that the left leg is not a valid unit of the character?

To expand, i created a tool that when you press it, it will fire an animation and make the other player take damage.

It says the players left leg is not a valid member of the character.

Here's the Local Script

local Animation = script.Animation
local Replicated = game:GetService("ReplicatedStorage")
local RemoteEvent = Replicated.Remotes.Punch

local Debounce = false

wait(2)

local Humanoid = game.Players.LocalPlayer.Character.Humanoid

script.Parent.Activated:Connect(function()
	if not Debounce then
		Debounce = true
	
	local AnimationTrack = Humanoid:LoadAnimation(Animation)
	RemoteEvent:FireServer()
	wait(2)
	Debounce = false 
	end
end)

Here's the server script:

local Tools = game:GetService("ReplicatedStorage"):WaitForChild("Tools")
local RemoteEvent = game:GetService("ReplicatedStorage").Remotes.Punch
local Animation = Tools.SuperPunch.PunchConnecter.Animation

wait(1)

RemoteEvent.OnServerEvent:Connect(function(player)
	local Hum = player.Character.Humanoid
	local AnimationTrack = Hum:LoadAnimation(Animation)
	AnimationTrack:Play()
	print("Hello!")
	
	if AnimationTrack.IsPlaying then
		local LeftArm = player.Character["Left Arm"]
		
		LeftArm.Touched:Connect(function()
		
			Hum:TakeDamage(10)
		print("Damaged another player!")
	end)
		end
		end

Perhaps you have to make your character R6. R15 characters don't have a body part called Left Arm.