Windows service not able to capture Login/Lock/Unlock

protected override void OnStart(string[] args)
{
  SystemEvents.SessionSwitch += SystemEvents_SessionSwitch;
  Console.ReadLine();
}

protected override void OnStop()
{
  SystemEvents.SessionSwitch -= SystemEvents_SessionSwitch;
}

static void SystemEvents_SessionSwitch(object sender, SessionSwitchEventArgs e)
{
  WriteToLogFile( e.Reason.ToString());
  if (e.Reason == SessionSwitchReason.SessionLock)
  {
    WriteToLogFile("SessionLock ");
  }
  if (e.Reason == SessionSwitchReason.SessionUnlock)
  {
    WriteToLogFile("SessionUnlock ");
  }
  if (e.Reason == SessionSwitchReason.SessionLogon)
  {
    WriteToLogFile("SessionLogon ");
  }
}