How to give a gui to a group of players on join?

I tried to edit a pre-made code so I could better understand how to do this:

peopleWhoGetGui = {"name", "name", "name", "name"} 
gui = game.Lighting.CommandBar

function isAllowed(name)
	for i,child in pairs(peopleWhoGetGui) do
		if string.lower(child) == string.lower(name) then
			return true
		end
	end
	return false
end

function onPlayerAdded(newPlayer)
	if isAllowed(newPlayer.Name) and newPlayer:findFirstChild("Humanoid") ~= nil then
		BackpackChanged(game.Players:findFirstChild(newPlayer.Name))
	end
end

function BackpackChanged(player)
	for i,wep in pairs(gui:getChildren()) do
		if wep.className == "ScreenGui" then
			if game:findFirstChild("PlayerGui") ~= nil then
				if game.PlayerGui:findFirstChild(wep.Name) == nil then
					wep:clone().Parent = player.PlayerGui
				end
			end
		end
	end
end

workspace.ChildAdded:connect(onPlayerAdded)

There are no errors but the code does not do what I want it to do. This is a "script" inside "Workspace" It's supposed to clone a gui from lighting and put it into the character's playergui Thanks In Advanced