I have a very simple master and content page based on it as a test
Here is the Master code:
<%@ Master Language="VB" CodeFile="t.master.vb" Inherits="t" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Untitled Page</title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:contentplaceholder id="ContentPlaceHolder1" runat="server">
</asp:contentplaceholder>
</div>
</form>
</body>
</html>
Here is the content page
<%@ Page Language="VB" MasterPageFile="~/t.master" AutoEventWireup="false" CodeFile="tm.aspx.vb" Inherits="tm" title="Untitled Page" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
Content Page<br />
<asp:UpdatePanel id="UpdatePanel1" runat="server">
<contenttemplate>
<fieldset>
<legend>UpdatePanel</legend>
<asp:Calendar id="Calendar1" runat="server"></asp:Calendar>
</fieldset>
</contenttemplate>
</asp:UpdatePanel>
</asp:Content>
I am using visual studio 2005 and getting the following error in the content page:
Error 54 Element 'UpdatePanel' is not a known element. This can occur if there is a compilation error in the Web site.
I am getting the same error for all controls inside the UpdatePanel - The contentTemplate and the calendar.
Here is my web.config part that relates to it
<add assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
Thanks in advance
Myalo