What's wrong with this script?

local MarketplaceService = Game:GetService("MarketplaceService")-- don't change
local ds = game:GetService("DataStoreService"):GetDataStore("PurchaseHistory")--don't change 

CASHID = 19680116 -- Put the Developer Product ID here

MarketplaceService.ProcessReceipt = function(receiptInfo) --dont change this!
    local playerProductKey = "player_" .. receiptInfo.PlayerId .. "_product_" .. receiptInfo.ProductId
    local numberBought = ds:IncrementAsync(playerProductKey, 1)
    for i,v in pairs (game.Players:GetChildren()) do
        if v.userId == receiptInfo.PlayerId then
            if receiptInfo.ProductId == CASHID then
                debounce = false
        h = Instance.new("Hat")
        p = Instance.new("Part")
        h.Name = "Unimaginative Doom"
        p.Parent = h
        p.Position = hit.Parent:findFirstChild("Head").Position
        p.Name = "Handle" 
        p.formFactor = 0
        p.Size = Vector3.new(1,1.20000005,1) 
        p.BottomSurface = 0 
        p.TopSurface = 0 
        p.Locked = true 
        script.Parent.Mesh:clone().Parent = p
        h.Parent = hit.Parent
        h.AttachmentPos = Vector3.new(0,-.9,0)
        wait(5)
        debounce = true


                    end
                end
            end
        end

    return Enum.ProductPurchaseDecision.PurchaseGranted  --Dont change this!    

It's for making a dominus infernous going on your head once you buy the product.