What's wrong with my skip stage script? --i know hardly anything about scripting.

The "xxxxxxxx" is my dev product that the user buys to skip a stage. This script works in Studio but not my game. I'm really confused as to why.

If anyone can help, that'd be great thanks.

> MarketplaceService = Game:GetService("MarketplaceService")
> 
> MarketplaceService.ProcessReceipt = function(receiptInfo)
> players = game.Players:GetPlayers()
> 
> currency = "Stage"
> 
> done = 0
> 
> for i=1,#players do
>   if players[i].userId == receiptInfo.PlayerId then
>       if receiptInfo.ProductId == xxxxxxxx and done == 0 then
>           done = 1
>           players[i].leaderstats[currency].Value = players[i].leaderstats[currency].Value + 1
>           players[i].Character.Humanoid.Health = 0
>           done = 0
>       end
>   end
> end
> return Enum.ProductPurchaseDecision.PurchaseGranted   
> end