Item(s) Not Showing Up Inside Of My Inventory Gui After The Item(s) Has Been Added To My Inventory?

I'm making a game like Miner's Haven and i'm making a inventory gui right now and I ran into a error.

Script(LocalScript):

local Inventory = script.Parent.Inventory
local StartingItems = {
	["Basic Iron Mine"] = 4,
	["Basic Furnace"] = 1,
	["Basic Conveyor"] = 10,
}

_G.CheckInventory = function(ItemName)
	for i,v in pairs(Inventory:GetChildren()) do
		if v.Name == ItemName then
			if v.Quantity.Value > 0 then
				return true
			end
		end
	end
end

_G.AddItemToInv = function(ItemName,Quantityy)
	local folder = Instance.new("Folder")
	folder.Name = ItemName
	local Quantity = Instance.new("NumberValue")
	Quantity.Name = "Quantity"
	Quantity.Value = Quantityy
	Quantity.Parent = folder
	folder.Parent = Inventory
end

wait(2)
repeat wait() until game.Players.LocalPlayer.Character
wait(1)
for i,v in pairs(StartingItems) do
	_G.AddItemToInv(i,v)
end

Inventory.ChildAdded:Connect(function(Child)
	local ItemFrame = script.Frame:Clone()
	ItemFrame.Parent = script.Parent.Background.Holder
	ItemFrame.Name = Child.Name
	ItemFrame.ItemImage = "rbxassetid://"..game:GetService("ReplicatedStorage").Items:FindFirstChild(Child.Name).Thumbnailid.Value
	ItemFrame.ItemName.Text = Child.Name
	ItemFrame.ItemQuantity.Text = "x"..Child.Quantity.Value
	ItemFrame.Visible = true
end)

It doesn't print an error or anything.