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