Can someone help me with this script?

Alright, so I'm trying to make a script where someone touches a brick. The first person to touch it becomes the owner. Then any further users who touch it will cause a GUI to send to the owner asking if they can join their team. If the owner presses yes, it will teleport the user in, if not, then nothing will happen. Here are the scripts:

The first script:

locked = false
tpTo = Vector3.new(0, 20, 0)
owner = ""
_G.names = {""}

script.Parent.Touched:connect(function(part)
    if part.Parent:FindFirstChild("Humanoid") then
        local name = part.Parent.Name

        if locked == false then
            owner = name
            locked = true
            part.Parent:MoveTo(tpTo) -- TELEPORT
            print("Owner touched the brick")
        else if locked == true and name ~= owner then
            table.insert(_G.names, name)
            game.Players[owner].PlayerGui.AskGui.Frame.Visible = true
            game.Players[owner].PlayerGui.AskGui.User.Text = name.." is asking to join your team. Accept this player?"
        end

    end
    end
    end)

And here is the localscript in the "Yes" button that the owner can press to accept a user:

tpTo = Vector3.new(0, 20, 0)
function tp()
game.Players[_G.names[#_G.names]].Character:MoveTo(tpTo)
script.Parent.Parent.Visible = false
end
script.Parent.MouseButton1Down:connect(tp)

I keep getting an error saying: "Players.Player1.PlayerGui.AskGui.Frame.Yes.LocalScript:3: attempt to get length of field 'names' (a nil value)"