Reportviwer control not working if i place inside the window
<form id="form1" runat="server">
            <ext:ResourceManager ID="ResourceManager1" runat="server" />
        
            <ext:Window 
                ID="formWindow" 
                runat="server" 
                Height="500" 
                Title="Customer Master" 
                ShowOnLoad="true" 
                CenterOnLoad="true"
                Resizable="true"
                Closable="false"
                MinWidth="800"
                Width="800" 
                Layout="Fit"
                Padding="2"
                Maximized="True">
                <Items>  <ext:Label ID="Label1" runat="server" Text=""></ext:Label></Items>
                <Content> 
                    <ajaxToolkit:ToolkitScriptManager runat="server" ID="scriptmgm1">
                        <Scripts>
                            <%--To learn more about bundling scripts in ScriptManager see http://go.microsoft.com/fwlink/?LinkID=272931&clcid=0x409 --%>
                            <%--Framework Scripts--%>                
                            <asp:ScriptReference Name="jquery" />
                            <asp:ScriptReference Name="jquery.ui.combined" />
                            <asp:ScriptReference Name="WebForms.js"  Path="~/Scripts/WebForms/WebForms.js" />
                            <asp:ScriptReference Name="WebUIValidation.js"  Path="~/Scripts/WebForms/WebUIValidation.js" />
                            <asp:ScriptReference Name="MenuStandards.js" Path="~/Scripts/WebForms/MenuStandards.js" />
                            <asp:ScriptReference Name="GridView.js" Path="~/Scripts/WebForms/GridView.js" />
                            <asp:ScriptReference Name="DetailsView.js"  Path="~/Scripts/WebForms/DetailsView.js" />
                            <asp:ScriptReference Name="TreeView.js"  Path="~/Scripts/WebForms/TreeView.js" />
                            <asp:ScriptReference Name="WebParts.js"  Path="~/Scripts/WebForms/WebParts.js" />
                            <asp:ScriptReference Name="Focus.js"  Path="~/Scripts/WebForms/Focus.js" />
                            <asp:ScriptReference Name="WebFormsBundle" />
                            <%--Site Scripts--%>
                        </Scripts>
                    </ajaxToolkit:ToolkitScriptManager> 
                    <asp:UpdatePanel ID="UpdatePanel1" runat="server">
                        <ContentTemplate>
                            <table style="width: 98%">
                                <tr>
                                    <td>                                       
                                <asp:Button ID="btndelete" runat="server" CssClass="btnalign" Text="Delete"  OnClientClick="return deleteRecord();" />--%>
                                        <ext:Button ID="btnPrint" runat="server" Text="Print" Icon="Printer" Cls="btnalign" StyleSpec="float:left; " >                                        
                                        </ext:Button>
                                        <ext:Button ID="btnExport" runat="server" Text="Export" Icon="PageExcel" Cls="btnalign" StyleSpec="float:left; " />
                                        <ext:Button ID="btnCancel" runat="server" Text="Cancel" Icon="Cancel" Cls="btnalign" StyleSpec="float:left; " />
                                    </td>
                                    <td style="width: 30%;">                                      
                                    </td>
                                    <td style="width: 20%">                                        
                                    </td>
                                </tr>
                            </table>
                            <fieldset >
                                <legend>List of Accounts
                                </legend>
                                <div style="height: 450px; margin-left: auto; margin-right: auto; overflow: auto; width: 100%;">
                                    <%-- Session Report Input --%>
                                    <section style="background-color: #D0DEF0; float: left; height: 450px; overflow: auto; width: 20%;">
                                        <table class="rpt_input" >                                             
                                            <tr>
                                                <td>
                                                    <asp:Label ID="Label2" runat="server" Text="Account Type" ></asp:Label>
                                                </td>
                                                <td><asp:DropDownList ID="DropDownList1" runat="server" Width="100"/></td>
                                            </tr>  
                                            <tr></tr>
                                            <tr></tr>
                                            <tr></tr>                                                                                        
                                        </table>   
                                        <table class="btn_input">                                                                                     
                                            <tr>
                                                <td>
                                                    <ext:Button ID="btnReport" runat="server" Text="Show" Icon="Report" Cls="btnalign" StyleSpec="float:left; " > 
                                                        <DirectEvents>
                                                            <Click OnEvent="BtnShowReport" >
                                                                <EventMask ShowMask="true" Msg="Verifying..." MinDelay="1000" />
                                                            </Click>
                                                        </DirectEvents>   
                                                    </ext:Button>                                                 
                                                    <ext:Button ID="Button4" runat="server" Text="Clear" Icon="PrinterCancel" Cls="btnalign" StyleSpec="float:left; " />
                                                </td>
                                                <td></td>
                                            </tr>
                                        </table>                                        
                                    </section>
                                    <%-- Session Report Control --%>
                                    <section style="float: left; height: 100%; width: 60%;">
                                        <rsweb:ReportViewer ID="ReportCOA" runat="server"></rsweb:ReportViewer>
                                    </section>
                                </div>
                            </fieldset> 
                        </ContentTemplate>
                    </asp:UpdatePanel>
                </Content>
            </ext:Window>
        </form>
var dtCoaReport = new DataTable();
            int branchId = 0;
            //ReportCOA.Reset();
            //ReportCOA.LocalReport.Refresh();
            dtCoaReport = new ClsCoaBal().GetChartofAccounts(branchId);            
            var reportDataSource = new ReportDataSource("rptCOA", dtCoaReport);
            ReportCOA.LocalReport.ReportPath = "UI/Reports/Reportfile/rpt_ChartofAccounts.rdlc";
            ReportCOA.LocalReport.DataSources.Add(reportDataSource);
            ReportCOA.LocalReport.Refresh();
            this.ReportCOA.Update();