Windows Phone 7 反序列化异常

>我正在尝试读取已使用序列化保存到隔离存储文件的XML文件。当我尝试在 try 块中读回 XML 文件时，它会在反序列化步骤中引发异常。我做错了什么吗？我该如何解决这个问题？

投注类别：

public class Bet
{
    public String Amount { get; set; }
    public String Opponent { get; set; }
    public String Terms { get; set; }
    public int Result { get; set; }
    public String ResultColor { get; set; }
    public Bet(String amount, String opponent, String terms, int result, String rcolor)
    {
        this.Amount = amount;
        this.Opponent = opponent;
        this.Terms = terms;
        this.Result = result;
        this.ResultColor = rcolor;
    }
}

保存/加载投注功能

public void SaveBets()
{
    List<Bet> bets = new List<Bet>();
    foreach (Bet item in openBetList)
        bets.Add(item);
    foreach (Bet item in closedBetList)
        bets.Add(item);
    // Write to the Isolated Storage
    XmlWriterSettings xmlWriterSettings = new XmlWriterSettings();
    xmlWriterSettings.Indent = true;
    using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
    {
        using (IsolatedStorageFileStream stream = myIsolatedStorage.OpenFile("Bets.xml", FileMode.Create))
        {
            XmlSerializer serializer = new XmlSerializer(typeof(List<Bet>));
            using (XmlWriter xmlWriter = XmlWriter.Create(stream, xmlWriterSettings))
            {
                serializer.Serialize(xmlWriter, bets);
            }
        }
    }
}
public void LoadBets()
{
    try
    {
        using (IsolatedStorageFile myIsolatedStorage = IsolatedStorageFile.GetUserStoreForApplication())
        {
            using (IsolatedStorageFileStream stream = myIsolatedStorage.OpenFile("Bets.xml", FileMode.Open))
            {
                XmlSerializer serializer = new XmlSerializer(typeof(List<Bet>));
                List<Bet> data = (List<Bet>)serializer.Deserialize(stream);
                if(data.Count > 0)
                    foreach (Bet item in data)
                    {
                        if (item.Result == 0)
                            openBetList.Add(item);
                        else
                            closedBetList.Add(item);
                    }
            }
        }
    }
    catch
    {
        //add some code here
    }
}

谢谢！