How Access TextChange event handler in DTE automation for the current active document

Hi,

   I want to be notified when there has been a change is the source document. I've tried implementing using DTE.Events.TextEditorEvents.LineChanged but it's not being called always. Am I missing something or can it be done in another way. This is the source code.

using System;
using System.Diagnostics;
using System.Globalization;
using System.Runtime.InteropServices;
using System.ComponentModel.Design;
using Microsoft.Win32;
using Microsoft.VisualStudio;
using Microsoft.VisualStudio.Shell.Interop;
using Microsoft.VisualStudio.OLE.Interop;
using Microsoft.VisualStudio.Shell;
using EnvDTE;

namespace Company.Auto
{
    /// <summary>
    /// This is the class that implements the package exposed by this assembly.
    ///
    /// The minimum requirement for a class to be considered a valid package for Visual Studio
    /// is to implement the IVsPackage interface and register itself with the shell.
    /// This package uses the helper classes defined inside the Managed Package Framework (MPF)
    /// to do it: it derives from the Package class that provides the implementation of the 
    /// IVsPackage interface and uses the registration attributes defined in the framework to 
    /// register itself and its components with the shell.
    /// </summary>
    // This attribute tells the PkgDef creation utility (CreatePkgDef.exe) that this class is
    // a package.
    [PackageRegistration(UseManagedResourcesOnly = true)]
    // This attribute is used to register the information needed to show this package
    // in the Help/About dialog of Visual Studio.
    [InstalledProductRegistration("#110", "#112", "1.0", IconResourceID = 400)]
    // This attribute is needed to let the shell know that this package exposes some menus.
    [ProvideMenuResource("Menus.ctmenu", 1)]
    [Guid(GuidList.guidAutoPkgString)]
    public sealed class AutoPackage : Package
    {
        private DTE dte;
        private OutputWindow outputWindow;
        private OutputWindowPane outputWindowPane;
        /// <summary>
        /// Default constructor of the package.
        /// Inside this method you can place any initialization code that does not require 
        /// any Visual Studio service because at this point the package object is created but 
        /// not sited yet inside Visual Studio environment. The place to do all the other 
        /// initialization is the Initialize method.
        /// </summary>
        public AutoPackage()
        {
            Debug.WriteLine(string.Format(CultureInfo.CurrentCulture, "Entering constructor for: {0}", this.ToString()));
        }



        /////////////////////////////////////////////////////////////////////////////
        // Overridden Package Implementation
        #region Package Members

        /// <summary>
        /// Initialization of the package; this method is called right after the package is sited, so this is the place
        /// where you can put all the initialization code that rely on services provided by VisualStudio.
        /// </summary>
        protected override void Initialize()
        {
            Debug.WriteLine (string.Format(CultureInfo.CurrentCulture, "Entering Initialize() of: {0}", this.ToString()));
            base.Initialize();

            // Add our command handlers for menu (commands must exist in the .vsct file)
            OleMenuCommandService mcs = GetService(typeof(IMenuCommandService)) as OleMenuCommandService;
            if ( null != mcs )
            {
                // Create the command for the menu item.
                CommandID menuCommandID = new CommandID(GuidList.guidAutoCmdSet, (int)PkgCmdIDList.cmdidMyCommand);
                MenuCommand menuItem = new MenuCommand(MenuItemCallback, menuCommandID );
                mcs.AddCommand( menuItem );
            }
        }
        #endregion

        /// <summary>
        /// This function is the callback used to execute a command when the a menu item is clicked.
        /// See the Initialize method to see how the menu item is associated to this function using
        /// the OleMenuCommandService service and the MenuCommand class.
        /// </summary>
        private void MenuItemCallback(object sender, EventArgs e)
        {
            this.dte = (DTE)GetService(typeof(DTE));
            string myString = "Name is " + dte.Name + "\rVersion is " + dte.Version;

            TextDocument txt = dte.ActiveDocument.Object("TextDocument") as TextDocument;
            txt.Selection.SelectAll();
            string s = txt.Selection.Text;
            Windows windows = dte.Windows;
            Window window = (Window)windows.Item("{34E76E81-EE4A-11D0-AE2E-00A0C90FFFC3}");
            window.Visible = true;

            this.outputWindow = (OutputWindow)window.Object;
            this.outputWindowPane = outputWindow.OutputWindowPanes.Add("Test");
            this.outputWindowPane.Activate();
            this.outputWindowPane.OutputString(s);

            dte.Events.TextEditorEvents.LineChanged += TextEditorEvents_LineChanged;

        }

        void TextEditorEvents_LineChanged(TextPoint StartPoint, TextPoint EndPoint, int Hint)
        {
            this.dte.Events.
            Debug.WriteLine("Check");
            TextDocument txt = this.dte.ActiveDocument.Object("TextDocument") as TextDocument;
            txt.Selection.SelectAll();
            string s = txt.Selection.Text;
            this.outputWindowPane.OutputString(s);
        }

    }
}