This script is too unreliable! Help?

Hey guys,

I have this script that check the player for a gamepass before making a GUI visible. The script however is too unreliable and keeps giving people bikes for free every once and a while! It's hurting my advertising profit and I have made losses over the last two weeks! ;-;

Does anyone have a solution with a better script?

--// Initialization

local GamePassService = game:GetService("GamePassService")

--// Variables

gamepass1 = 256633733

--// Functions

function onCharacterSpawn(character)
  local player = game.Players:GetPlayerFromCharacter(character)

  if GamePassService:PlayerHasPass(player, gamepass1) then
    script.Parent.Parent.Spawn.Visible = true
    script.Parent.Visible = false
    script.Parent.Parent.Parent.OwnedBikes.Bike12.Visible = true
  end
end

--// Triggers

game.Workspace.ChildAdded:connect(onCharacterSpawn)

Cheers,

Michael