I want sub directories In my code inTreeview Infragistics

How to get the Sub directories also In my code. I am using Silverlight Application.Please send me the code.

XML File:

XAML Code :

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:d="http://schemas.microsoft.com/expression/blend/2008"

xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"

xmlns:ig="http://schemas.infragistics.com/xaml"

mc:Ignorable="d"

d:DesignHeight="300" d:DesignWidth="400">

Code-Behind File:

using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.IO;

using System.Linq;

using System.Net;

using System.Windows;

using System.Windows.Controls;

using System.Windows.Documents;

using System.Windows.Input;

using System.Windows.Media;

using System.Windows.Media.Animation;

using System.Windows.Resources;

using System.Windows.Shapes;

using System.Xml;

using System.Xml.Linq;

namespace Infragistics_SilverLight

{

public partial class TreeDemo : UserControl

{

public TreeDemo()

{

InitializeComponent();

Read();

}

public class Book

{

public string Author { get; set; }

public string Title { get; set; }

public string UnitPrice { get; set; }

public string Url { get; set; }

public decimal Price { get; set; }

public string ReleaseDate { get; set; }

public IEnumerable Chapters { get; set; }

public XNode node { get; set; }

}

public class Chapter

{

public string Title { get; set; }

public string Author { get; set; }

public string UnitPrice { get; set; }

public XNode node { get; set; }

}

private IEnumerable GetChapters(XElement parent)

{

return (from d in parent.Descendants("chapter")

select new Chapter

{

Title = d.Attribute("Title").Value,

node = d

}).ToList();

}

//private void MyTree_ActiveItemChanged_1(object sender, Infragistics.Controls.Menus.ActiveItemChangingEventArgs e)

//{

// //txtBox.Text += PrintLog(DataTreeStrings.XDT_ActiveNodeChanged);

//}

public void Read()

{

try

{

XDocument doc = XDocument.Load("Books.xml");

var dataSource = (from d in doc.Descendants("book")

where (d.Descendants("chapter") != null && d.Descendants("chapter").Count() > 0)

select new Book

{

Author = d.Attribute("Author").Value,

Title = d.Attribute("Title").Value,

UnitPrice = d.Attribute("UnitPrice").Value,

Url = d.Attribute("Url").Value,

ReleaseDate = d.Attribute("ReleaseDate").Value,

Chapters = this.GetChapters(d),

node = d

});

this.MyTree.ItemsSource = dataSource.ToList();

}

catch (Exception)

{

throw;

}

private void MyTree_ActiveItemChanged_2(object sender, EventArgs e)

{

}