03:16:36.979 - Banlist is not a valid member of PlayerGui
The Banlist ist a ScreenGui.
thats the script placed in StarterGui:
if script.Parent.Parent.Name == "Player" then
Reason = "Name 'Player' is'nt Allowed!"
script.Parent.Banlist.Frame.Visible = true
script.Parent.Banlist.Frame.Grund.Text = "Banned, Reason: " ..Reason
script.Parent.Parent.Character:remove()
end

1 comment
Put "wait(1)" at the very beginning of the script. You need time to wait for the player and it's assets to load.