Script not sending out messages in chat?

-->>: System messages

function makeSystemMessage(text, font, color)
    game.StarterGui:SetCore("ChatMakeSystemMessage", { -- Creates message
        Text = text;
        Font = font;
        Color = Color3.new(color)
    })
end

while wait(40) do
    makeSystemMessage("Having fun? Leaving a like on the game would be appreciated!", Enum.Font.Arial, "Cyan")
end

-- Sends a message when a player joins
game.Players.PlayerAdded:Connect(function(player)
    makeSystemMessage(player.Name.." has joined the game!", Enum.Font.Arial, "Deep Orange")
end)

-- Sends a message when a player leaves
game.Players.PlayerRemoving:Connect(function(player)
    makeSystemMessage(player.Name.." has left the game!", Enum.Font.Arial, "Deep Orange")
end)

This script is supposed to say things in chat when a player joins and leaves and such. But it doesn't work. This is a local script as well, I also tried it in a script and it didn't work-It told me to use a local script basically. The local script doesn't work though, whats wrong?