Why isn't my anti exploit script isnt detecting ChildAdded?

local reason
game.Players.ChildAdded:Connect(function(plr)
    local function kick()
        plr:Kick(reason)
    end
    plr:WaitForChild("PlayerGui").ChildAdded:Connect(function(child)
        if child:IsA("ScreenGui") then
            if child.Name == "BubbleChat" or child.Name == "Chat" or child.Name == "Freecam" then
                print('loaded')
            else            
                local reason = 'Executing a ScreenGUI'
                print(reason)
                kick()
            end

        end
    end)
end)

So, whenever I join the game, the first thing I see in the output is "loaded" because I made it print loaded whenever a child with the name "BubbleChat", "Chat", or "Freecam" is added into PlayerGui.

But. whenever I go into Explorer (in-game) and insert a new ScreenGui into my PlayerGui, it is supposed to kick the player and print the reason, "Executing a ScreenGUI". But unfortunately, it doesn't do that.

I really do not know what the error is here. There is no error in the output. Help is greatly appreciated!