How do I make a working material ESP for admins?

I'm making a game and I'd like to give my admins ESP for other players and ores around them. I've tried to make an iron ESP but it doesn't seem to work. There are no errors when the script is ran, but the ESP does not come up. Please help.

local ESP = Instance.new('BillboardGui');
ESP.Parent = game:GetService("ReplicatedStorage");
ESP.Name = "ESP";

local textLabel = Instance.new('TextLabel');
textLabel.Parent = ESP;
textLabel.Text = "Iron";
textLabel.Font = Enum.Font.ArialBold;
textLabel.Size = UDim2.new(1, 0, 1, 0);
textLabel.TextSize = 24;
textLabel.TextColor3 = Color3.fromRGB();
textLabel.TextStrokeTransparency = 0.25;

local ores = game.Workspace.OreZones:GetDescendants()
local doors = game.Workspace.Doors
local trees = game.Workspace.Trees

for i,v in pairs(ores) do
   if v.Name == "IronNode" then
       game:GetService('CoreGui').ESP:Clone()
       game:GetService('CoreGui').ESP.Parent = game.Players.LocalPlayer.PlayerGui
       game:GetService('CoreGui').ESP.Adornee = v.RockPrim
   end
end

You are not allowed to add items to the CoreGUI. Use the player his PlayerGui. Keep an instance you want to clone in ReplicatedStorage as a template.