Help with Developer Product?

I tried to do this in a LocalScript, but it does not work and I can't figure out why because it doesn't throw any errors. Please help!

script.Parent.MouseButton1Click:connect(function()
    if game.Players.LocalPlayer.items.numPagesInv.Value == 1 then
        game:GetService("MarketplaceService"):PromptProductPurchase(game.Players.LocalPlayer, script.Parent.devId.Value)
        game:GetService("MarketplaceService").ProcessRecepit = function(receiptInfo)
            if receiptInfo.ProductId == script.Parent.devId.Value then
                game.Players.LocalPlayer.items.numPagesInv.Value = game.Players.LocalPlayer.items.numPagesInv.Value + 1
            end
        end
        return Enum.ProductPurchaseDecision.PurchaseGranted
    elseif game.Players.LocalPlayer.items.numPagesInv.Value == 2 then
        script.Parent.Parent:TweenPosition(UDim2.new(-1, 0, .15, 0), "Out", "Sine", .5, true)
        wait(.7)
        script.Parent.Parent.Parent.page2:TweenPosition(UDim2.new(0, 0, .15, 0), "In", "Sine", .5, true)
    end
end)