Tool Dev Product?

I am trying to make a Developer Product give a tool after the player purchase's it,

-- setup local variables
local MarketplaceService = Game:GetService("MarketplaceService")
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")
local productId = 19181612

game.Players.PlayerAdded:connect(function()
	print("start")
local DeveloperProducts = game:GetService("MarketplaceService"):GetDeveloperProductsAsync():GetCurrentPage()
for _, DevProductContainer in pairs(DeveloperProducts) do
    for Field, Value in pairs(DevProductContainer) do
        print(Field .. ": " .. Value)
    end
    print(" ")
end
print("end")
end)

-- define function that will be called when purchase finished
MarketplaceService.ProcessReceipt = function(receiptInfo) 

	-- find the player based on the PlayerId in receiptInfo
	for i, player in ipairs(game.Players:GetChildren()) do
		if player.userId == receiptInfo.PlayerId then
			
			
			-- check which product was purchased
			if receiptInfo.ProductId == productId then
				
				-- handle purchase. In this case we are healing the player.
				game.Lighting["Tool"]:clone().Parent = player.BackPack
				-- more feedback for the player.
				game.Workspace.DisplayScreen.SurfaceGui.TextBox.Text = player.Name .. " has purchased a healing potion."
			end
		end
	end	
	
	-- record the transaction in a Data Store
	local playerProductKey = "p_" .. receiptInfo.PlayerId .. "_p_" .. receiptInfo.PurchaseId
	ds:IncrementAsync(playerProductKey, 1)	
	
	-- tell ROBLOX that we have successfully handled the transaction
	return Enum.ProductPurchaseDecision.PurchaseGranted		
end

Anyone know why this won't work??