Why wont my scripts work for Developer Products? (Please Help, I really want to learn Dev Products)

I thought I knew what I was doing for this but it appears it doesn't work. I have a script inside of Workspace and a local script inside of StarterPack. What I did notice when I joined the game is this error: httpGet http://www.roblox.com/Persistence/GetBlobUrl.ashx?placeid=208825286&userid=29413559 failed. Trying again. Error: HTTP 404 (Not Found). Elapsed time: 0.126001

and in Red: Content failed because HTTP 404 (Not Found)

I don't think that even matters because at the same exact time, all the printing in the script seems to go on. (Found those things with Developer Console)

This is my script in Workspace:

-- setup local variables
local MarketplaceService = game:GetService("MarketplaceService")
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")
local productId = 22702178 --Speed Increase +2
local productId2 = 22702183 --Speed Increase +2 [No Stacking]

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 for productId
                player.Character.Humanoid.WalkSpeed = player.Character.Humanoid.Walkspeed + 2
            elseif receiptInfo.ProductId == productId2 then
                -- handle purchase for productId2
                player.Character.Humanoid.WalkSpeed = 18
            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

Now in StarterPack, I have this script:

-- setup local variables
local StackableSpeed = game.StarterGui.Store.Holder.CoreGui.StackableSpeed
local NoStackSpeed = game.StarterGui.Store.Holder.CoreGui.NoStackSpeed
local productId = 22702178 --Speed Increase +2
local productId2 = 22702183 --Speed Increase +2 [No Stacking]

-- when player clicks on buy brick prompt him/her to buy a product
StackableSpeed.MouseButton1Click:connect(function()
    game:GetService("MarketplaceService"):PromptProductPurchase(game.Players.LocalPlayer, productId)
end)

NoStackSpeed.MouseButton1Click:connect(function()
    game:GetService("MarketplaceService"):PromptProductPurchase(game.Players.LocalPlayer, productId2)
end)

If you need more information or anything such as my Hierarchy, please tell me and i'll do what I can to provide!