Why doesn't this script process the PromptPurchaseFinished function?

            local MarketplaceService = game:GetService("MarketplaceService")
            local buyButton = game.Workspace["Coin Stand"].Part.SurfaceGui.Frame["1000"]
            local player = game.Players.LocalPlayer
            local id = 25821928
            local isPurchased = true
        buyButton.MouseButton1Click:connect(function()

    MarketplaceService:PromptProductPurchase (player, id, true,  2)


        MarketplaceService.PromptPurchaseFinished:connect(function(player, id, isPurchased)
            if isPurchased then
    player.leaderstats.Coins = game.Players.LocalPlayer.leaderstats.Coins +1000 
end 
    end)
        end) 

Basically a long time ago I created a leaderboard script, it works.

Now after I buy the item, I don't get an extra 1,000 coins to use as I please.... In fact, this line;

MarketplaceService.PromptPurchaseFinished:connect(function(player, id, isPurchased)
            if isPurchased then

Doesn't even run, because apparently even though I'm buying it, It returns false? I even stated that it is true above..

I have used the wiki for this PromptPurchaseFinished part... let's just say the wiki needs a clearer explanation.

And all It needs to do is return true as I am wasting one tix every time I test this code :'(