What does this PromptProductPurchase error mean?

PurchasePromptScript: getProductInfo failed because MarketplaceService:getProductInfo() failed because rawProductInfo was empty Make sure a valid ID was specified <

LocalScript:

local MPS = game:GetService("MarketplaceService")
local RPS = game:GetService("ReplicatedStorage")

script.Parent.MouseButton1Click:connect(function()
	MPS:PromptProductPurchase(game.Players.LocalPlayer, 643910613)
end)

RPS.Events.BuyPrompt.OnClientEvent:connect(function(player, product)
	if product == "Upgrade" then
		script.Parent.Text = "You Own This Item"
	end
end)

Main Script:

local MPS = game:GetService("MarketplaceService")
local RPS = game:GetService("ReplicatedStorage")
local product = ""

MPS.ProcessReceipt = function(purchaseInfo)
	local player = game:GetService("Players"):GetPlayerByUserId(purchaseInfo.PlayerId)
	if purchaseInfo.ProductId == 643910613 then
		product = "Upgrade"
		RPS.Events.BuyPrompt:FireClient(product)
	elseif purchaseInfo.ProductId == 653173240 then
		product = "Elite"
		RPS.Events.BuyPrompt:FireClient(product)
	elseif purchaseInfo.ProductId == 659939994 then
		product = "Palace"
		RPS.Events.BuyPrompt:FireClient(product)
	end
	return Enum.ProductPurchaseDecision.PurchaseGranted
end

The error means that it cannot do PromptProductPurchase because the ID is wrong or it cannot find the ID. Double check the IDs in your scripts.