Sorry for the delay,
No one replied to me except you,
Here is my html code,
<%@ Register TagPrefix="uc1" TagName="LMSWelcome" Src="LMSWelcome.ascx" %>
<%@ Register TagPrefix="uc1" TagName="LMSTopBanner" Src="LMSTopBanner.ascx" %>
<%@ Page Language="vb" AutoEventWireup="false" Codebehind="LMSLessonPage.aspx.vb" Inherits="ThinClientInterface.LMSLessonPage"%>
<%@ Register TagPrefix="uc1" TagName="LMSStudentMenu" Src="LMSStudentMenu.ascx" %>
<%@ Register TagPrefix="iewc" Namespace="Microsoft.Web.UI.WebControls" Assembly="Microsoft.Web.UI.WebControls, Version=1.0.2.226, Culture=neutral, PublicKeyToken=31bf3856ad364e35" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<title>Launch Lesson</title>
<LINK href="styles.css" type="text/css" rel="stylesheet">
<meta content="Microsoft Visual Studio.NET 7.0" name="GENERATOR">
<meta content="Visual Basic 7.0" name="CODE_LANGUAGE">
<meta content="JavaScript" name="vs_defaultClientScript">
<meta content="
name="vs_targetSchema">
<script language="javascript" src="Help/MapIDs.js"></script>
<script language="javascript" src="Help/Student/CallHelp.js"></script>
<script language="javascript" src="Help/RoboHelp_CSH.js"></script>
<script language="javascript">
</script>
<script id="clientEventHandlersJS" language="javascript">
<!--
var i = 0
function RefreshLessonTree()
{
//alert("RefreshLessonTree"

;
if(i == 1 )
{
window.navigate(window.document.URLUnencoded);
}
else
i = i + 1;
}
function window_onload() {
//alert("window_onload"

;
}
function window_onfocus() {
RefreshLessonTree();
}
function tv_onClick()
{
i = 1;
}
function tv_onCollapse()
{
i = 0;
}
function tv_onExpand()
{
i = 0;
}
//-->
</script>
</HEAD>
<body id="BlueBg" MS_POSITIONING="GridLayout" language="javascript" oncontextmenu="return false;" onload="return window_onload()" onfocus="return window_onfocus()">
<form id="Form1" method="post" runat="server">
<TABLE id="Table4" style="Z-INDEX: 103; LEFT: -10px; POSITION: absolute; TOP: -5px" cellSpacing="0" cellPadding="0" border="0">
<TR>
<TD>
<uc1:LMSTopBanner id="LMSTopBanner1" runat="server"></uc1:LMSTopBanner></TD>
</TR>
</TABLE>
<INPUT id="txtLegacy" style="Z-INDEX: 104; LEFT: 550px; VISIBILITY: hidden; WIDTH: 18px; POSITION: absolute; TOP: 15px; HEIGHT: 22px" type="text" size="1" value="0" name="txtLegacy" runat="server">
<TABLE id="Table9" style="Z-INDEX: 104; LEFT: 192px; WIDTH: 758px; POSITION: absolute; TOP: 129px; HEIGHT: 224px" borderColor="black" cellSpacing="1" cellPadding="1" width="738" border="1">
<TR>
<td valign="center" bgColor="#a6a592" style="WIDTH: 63px">
<asp:label id="lblSelCourseName" runat="server" CssClass="clsBlueBoldLabel_12" ForeColor="Black" Height="14" Width="684px">System Statistics</asp:label>
</td>
<td valign="center" bgColor="#a6a592" style="WIDTH: 3px; HEIGHT: 26px">
<asp:HyperLink id="HlNotepad" runat="server" Width="25px" ToolTip="Notepad" ImageUrl="Icons/Notepad.gif" Target="_self">Notepad</asp:HyperLink>
</td>
<td valign="center" bgColor="#a6a592" style="WIDTH: 3px;HEIGHT: 26px">
<asp:HyperLink id="HPrintNotes" runat="server" Width="25px" ToolTip="Print Notes" ImageUrl="Icons/printer_s.jpg" Target="_self">Notepad</asp:HyperLink>
</td>
</TR>
<TR>
<td colspan="3" align="left" bgColor="wheat" borderColor="#e6e6fa">
<P>
<asp:label id="lblMsg" runat="server" ForeColor="Crimson" CssClass="clsErrorMessage" Width="812px" BorderColor="Transparent" BorderStyle="None" Visible="False" BackColor="Transparent"></asp:label></P>
<P>
<iewc:treeview id="tvLessonStructure" runat="server" BorderStyle="Solid" Height="400px" Width="815px" BorderColor="Black" ShowLines="False" BorderWidth="1px" SelectExpands="True" ShowPlus="False">
<iewc:TreeNodeType DefaultStyle="font-weight:normal;font-size:15px;color:black;font-family:Tahoma;" Type="blockCBT"></iewc:TreeNodeType>
<iewc:TreeNodeType DefaultStyle="font-weight:normal;font-size:15px;color:black;font-family:Tahoma;" Type="lessonCBT"></iewc:TreeNodeType>
</iewc:treeview></P>
</td>
</TR>
<tr>
<td colspan="3" borderColor="lavender" style="HEIGHT: 41px">
<table style="FONT-WEIGHT: bold; FONT-SIZE: 10px; WIDTH: 815px; COLOR: black; FONT-FAMILY: Tahoma; HEIGHT: 40px; BACKGROUND-COLOR: #a6a592" borderColor="lightsteelblue" borderColorDark="#b0c4de" width="815" borderColorLight="#b0c4de">
<tr>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image6" runat="server" Height="17px" Width="17px" ImageUrl="Icons/Globe.gif"></asp:Image>
<FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">WBT</FONT>
</td>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image7" runat="server" Height="17px" Width="17px" ImageUrl="Icons/CD.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">CBT</FONT>
</td>
</tr>
<tr>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image4" runat="server" Height="17px" Width="17px" ImageUrl="Icons/block.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">
Block</FONT>
</td>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image5" runat="server" Height="17px" Width="17px" ImageUrl="Icons/Lessons.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">Lesson</FONT>
</td>
</tr>
<tr>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image1" runat="server" Height="17px" Width="17px" ImageUrl="Icons/NotAttempted.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">Not
Attempted</FONT>
</td>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image2" runat="server" Height="17px" Width="17px" ImageUrl="Icons/InComplete.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">Incomplete</FONT>
</td>
<td vAlign="center" style="WIDTH: 160px">
<asp:Image id="Image3" runat="server" Height="17px" Width="17px" ImageUrl="Icons/Complete.gif"></asp:Image><FONT style="FONT-WEIGHT: normal; FONT-SIZE: 11pt; FONT-FAMILY: Tahoma">Complete</FONT>
</td>
</tr>
</table>
</td>
</tr>
<tr bordercolor="#003300">
<td colspan="3" style="HEIGHT: 40px" align="middle">
<asp:Button id="btnBack" runat="server" Width="110px" Text="<< Back" Height="25px" CssClass="clsSubmitButton"></asp:Button>
</td>
</tr>
</TABLE>
<asp

anel id="pnlMenu" style="Z-INDEX: 101; LEFT: -1px; POSITION: absolute; TOP: 48px" runat="server" Width="185px" CssClass="clsPanel" Height="600px">
<TABLE id="Table2" style="WIDTH: 185px; HEIGHT: 40px" borderColor="#000000" cellSpacing="0" cellPadding="0" width="174" border="0">
<TR height="64">
<TD style="BACKGROUND-REPEAT: repeat-x" vAlign="top" background="Images/red-top-edge.jpg"></TD>
</TR>
<TR height="660">
<TD style="BACKGROUND-REPEAT: repeat-y" vAlign="top" background="Images/big-horizontal-red-line.jpg">
<uc1:LMSStudentMenu id="usrCtrlStudentMenu" runat="server"></uc1:LMSStudentMenu></TD>
</TR>
</TABLE>
</asp

anel>
<TABLE id="Table3" style="Z-INDEX: 102; LEFT: 184px; POSITION: absolute; TOP: 48px" cellSpacing="0" cellPadding="0" width="300" border="0">
<TR>
<TD>
<uc1:LMSWelcome id="LMSWelcome1" runat="server"></uc1:LMSWelcome></TD>
</TR>
</TABLE>
</form>
</body><script src="LMSChildWindowSettings.js" language="javascript" type="text/javascript"></script>
</HTML>
I'am not doing anything with treeview control in my codebehind except populating it in pageload event.
Thankyou very much