Onchatted script not working?

local isAdmin = {["JonathanW123"] = true, ["CorruptBullet"] = true, ["Player"] = true}

function onChatted(message, player)
    if message == "Hi" and isAdmin[player.Name] then
     local m = Instance.new("Message")
m.Parent =  game.Workspace
m.Text = " is here"
    end
end