Десериализация XML

  public partial class Form1 : Form
    {
        List<Transport> listOfTransportFirst = new List<Transport>();
 
        Dictionary<int, Transport> listOfTransportDict = new Dictionary<int, Transport>();
        
        int idTransport, middleSpeed, numberOfPassengers, costTravel, maximumTravelDistance;
        string name;

  public void DictionaryAdd()
        {
            listOfTransportDict.Add(1, new Balloon(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
            listOfTransportDict.Add(2, new Trains(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
            listOfTransportDict.Add(3, new Ships(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
            listOfTransportDict.Add(4, new Cars(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
            listOfTransportDict.Add(5, new UnderWaterTransport(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
            listOfTransportDict.Add(6, new Aircraft(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance));
        }

   private void button3_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() != DialogResult.Cancel)
            {
                string filename = openFileDialog1.FileName;
 
                using (FileStream TransportFile = new FileStream(filename, FileMode.OpenOrCreate))
                {
                    DictionaryAdd();
 
                    List<Transport> listOfTransportSecond = new List<Transport>();
                    XmlSerializer formatter = new XmlSerializer(listOfTransportSecond.GetType());
                
                    List<Transport> listOfTransport = (List<Transport>)formatter.Deserialize(TransportFile);
 
                    listOfTransport.Add(listOfTransportDict[]);
                    
                    listBox2.Items.Add(listOfTransport);
                }
            }
               
        }

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Serialization;
 
namespace laba3
{
    [Serializable][XmlInclude(typeof(Transport))]
     public class Balloon:Transport
    {
    
        public Balloon()
        {
            
        }
        public Balloon(int idTransport, int middleSpeed, int numberOfPassengers, int costTravel, string name, int maximumTravelDistance)
             : base(idTransport, middleSpeed, numberOfPassengers, costTravel, name, maximumTravelDistance)
        {
 
        }
    }
}

listOfTransport.Add(listOfTransportDict[]);