.NET Error Closing serial port BaseStream error is only available when the port is open

I'm using the .NET System.IO.Ports.SerialPort using the BaseStream as suggested in this post <a href="http://www.sparxeng.com/blog/software/must-use-net-system-io-ports-serialport">If you must use NET SerialPort</a>


But when I try to close the port or the baseStream, an System.InvalidOperationException is raised saying &quot;The BaseStream is only available when the port is open&quot;

This is my code:

  <pre lang="c#">  
        private void ActionStarted()
        {
            //ajusta el puerto
            setupSerial();

            serial.Open();  //conecta al plc
            byte[] buffer = new byte[15];
            Action kickoffRead = null;
            
            if (serial.IsOpen) //si esta abierto el puerto hace todo esto
            {
                kickoffRead = delegate()
                {
                    serial.BaseStream.BeginRead(buffer, 0, buffer.Length,
                        delegate(IAsyncResult ar)
                        {
                            try
                            {
                                int actualLength = serial.BaseStream.EndRead(ar);
                                byte[] received = new byte[actualLength];
                                Buffer.BlockCopy(buffer, 0, received, 0, actualLength);
                                raiseAppSerialDataEvent(received);
                            }
                            catch 
                            {
                               
                            }

                            kickoffRead();

                        }, null);
                };
                kickoffRead();
            }
            
        }

//<-- here is where the error occurs -->
 private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
        {
        serial.BaseStream.Flush();
        serial.BaseStream.Close();
        serial.Close();            
         }