mainmenu/on works but not mainmenu/off, can someone help?

So I have a script where if you say mainmenu/on, or off, it will make the mainmenu pop up. Well for some reason when I tested it I said "mainmenu/on", it worked, but when I tried mainmenu/off, it did not go away. Can someone fix this? Here's the script, if you could please?

local function onChatted(msg, recipient, speaker)

local msg = msg:lower()

if msg == "mainmenu/on" then

if not speaker.PlayerGui["ScreenGui"].Frame.Visible == true then

speaker.PlayerGui["ScreenGui"].Frame.Visible = true

elseif msg == "mainmenu/off" then
	
if not speaker.PlayerGui["ScreenGui"].Frame.Visible == false then
	
speaker.PlayerGui["ScreenGui"].Frame.Visible = false

end

end

end

end

 

function onPlayerEntered(newPlayer)

 

newPlayer.Chatted:connect(function(msg, recipient) onChatted(msg, recipient, newPlayer) end)

end

 

 

game.Players.PlayerAdded:connect(onPlayerEntered)

Try, if that works.

local function onChatted(msg, recipient, speaker)
	local msg = msg:lower()
	if msg == "mainmenu/on" then
		speaker.PlayerGui["ScreenGui"].Frame.Visible = true
	end
	if msg == "mainmenu/off" then
		speaker.PlayerGui["ScreenGui"].Frame.Visible = false
	end
end

function onPlayerEntered(newPlayer)
	newPlayer.Chatted:connect(function(msg, recipient) onChatted(msg, recipient, newPlayer) end)
end

game.Players.PlayerAdded:connect(onPlayerEntered)