Why won't the backpack weld to the person?

local self = script
local Char = self.Parent
local TestingPack = game:GetService("ReplicatedStorage"):WaitForChild("InfBackpack")
local Clone = TestingPack:Clone()

local WeldPack = function(Part0, Part1)
	Clone.Parent = Char
	Part1.CFrame = Char:WaitForChild("UpperTorso").CFrame
	local Weld = Instance.new("ManualWeld", Part1)
	Weld.Part0 = Part0
	Weld.Part1 = Part1
	Weld.C0 = Part0.CFrame:inverse() * Char:WaitForChild("UpperTorso").CFrame
end

WeldPack(Clone:WaitForChild("InfBackpack"), Char:WaitForChild("UpperTorso"))

This script is supposed to weld the backpack to the persons back, why won't it work, btw no errors in the script.