MarketplaceService buy not working?

In this script located in server script service, it detects when the developer prompt has been accepted it would print "added song" -- for test reasons, although it doesn't print it when you accept the prompt

local MarketplaceService = game:GetService("MarketplaceService")

local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")

------------------------------------------------------------

MarketplaceService.ProcessReceipt = function(receiptInfo)

for i, player in pairs(game.Players:GetChildren()) do

if player.userId == receiptInfo.PlayerId then

table.insert(que,game.Players[player].PlayerGui.ScreenGui.show.request.theuid.Text)

print("added song")

end

end



local playerProductKey = receiptInfo.PlayerId .. receiptInfo.PurchaseId

ds:IncrementAsync(playerProductKey, 506263839)



return Enum.ProductPurchaseDecision.PurchaseGranted

end