One out of multiple dev products working?

I have multiple dev product scripts that give you something different depending on what product you buy. I have a shop gui where you can select which product you want to buy. Then I have a script for each product in the ServerScriptService that detects when a product is bought and give the player what they bought. My problem is that every time I go into the game only one product works and its random every time. Theres also no errors in the output. I'm not sure what's happening, please help! Heres the script:

local mkps = game:GetService("MarketplaceService")
local ProductId = 1291342629
local character = game.Players.LocalPlayer



local function processReceipt(receiptInfo)
    local player = game.Players:GetPlayerByUserId(receiptInfo.PlayerId)
    local gui = player.PlayerGui.Stats.Timer -- timer
    local none = player.PlayerGui.Stats.None -- "none" text for when the timer is done
    local NoBuy = player.PlayerGui.Shop.WalkingProducts.NoBuy
    local NoBuyText = player.PlayerGui.Shop.WalkingProducts.NoBuyStackText
    if not player then
        return Enum.ProductPurchaseDecision.NotProcessedYet

    elseif player then
        if receiptInfo.ProductId == ProductId then
            none.Visible = false
            gui.Visible = true
            NoBuy.Visible = true
            NoBuyText.Visible = true
            print("player bought 30 min of time")
            player.Character.Humanoid.WalkSpeed = 16 -- changes player walk speed from 0 to 16
            for i = 1800, 1, -1 do -- sets 30 second timer
                gui.Text = tostring(i)
                wait(1)
            end
            gui.Visible = false
            none.Visible = true
            NoBuy.Visible = false
            NoBuyText.Visible = false
            player.Character.Humanoid.WalkSpeed = 0 -- back to 0 walkspeed when 30 seconds are done
        end

        return Enum.ProductPurchaseDecision.PurchaseGranted
    end
end

mkps.ProcessReceipt = processReceipt

Its the same script for each dev product it just has a different productID and a different reward