(Error creating control-updatepanel server tag is not well formed) how to remove this from design view

See more:

C#

<%@ Page Title="" Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Diamond.aspx.cs" Inherits="Diamond" %>


<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">

.auto-style7 {
width: 649px;
}


<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:ScriptManager ID="ScriptManager1" runat="server">

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
<contenttemplate>

<asp:Label ID="lblCategoryName" runat="server" Text="Label" ForeColor="#CC00FF" Font-Size="Large"> <asp:Label ID="Label2" runat="server" Text="Category" Font-Size="Large" ForeColor="#CC00FF">

<asp:Panel ID="pnlProduct" runat="server" BorderColor="Black" BorderStyle="Inset" BorderWidth="1px" Height="500px" ScrollBars="Auto"> <asp:DataList ID="dlProduct" runat="server" RepeatColumns="3" Width="600px"> <itemtemplate> <asp:Label ID="lblProductName" runat="server" Text="<%#Eval("product_name") %>" Style="font-weight:700"> "> " alt="" /> <asp:Label ID="lblPrice" runat="server" Text='<%#Eval("product_price")%>'> <asp:Panel ID="Panel1" runat="server" BorderColor="Black" BorderStyle="Inset" BorderWidth="1px" Height="500px" ScrollBars="Auto"> <asp:DataList ID="dlCategory" runat="server" BackColor="White" GridLines="Horizontal" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px" CellPadding="4" ForeColor="Black" > <FooterStyle BackColor="#CCCCCC" ForeColor="Black" /> <HeaderStyle font-Bold="True" ForeColor="White" BackColor="#333333" /> <itemtemplate> <asp:LinkButton ID="lbtnCategoryname" runat="server" Text="<%#Eval("category_name") %>" CommandArguement="<%#Eval("category_Id") %>" > <SelectedItemStyle BackColor="#CC3333" Font-Bold="True" ForeColor="White" />

What I have tried:

<%@ Register Assembly="AjaxControlToolkit" Namespace="AjaxControlToolkit" TagPrefix="asp" %>


tried this still not working