Making arm follow camera with a skinned mesh?

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#1 
local arm = script.Parent.HumanoidRootPart:FindFirstChild("mixamorig:Hips"):FindFirstChild("mixamorig:Spine"):FindFirstChild("mixamorig:Spine1"):FindFirstChild("mixamorig:Spine2"):FindFirstChild("mixamorig:RightShoulder")
local player = game.Players.LocalPlayer
local mouse = player:GetMouse()

local function updateArm()
    local target = mouse.Hit.p
    local rotation = CFrame.lookAt(arm.Position, target)
    arm.CFrame = rotation * CFrame.new(arm.Position)
end

game:GetService("RunService").RenderStepped:Connect(updateArm)

I’m trying to get the arms to follow the camera however, im using a skinned mesh this is what i made and the arm just gets tped into the abyss