UpdatePanel is not known elements.This can occur if compilation error in website
<p>I have created one master page and one content page.Added scripManager in master page(contentplaceholder) and update panel in content page.But I am getting an error <code>"UpdatePanel is not known elements"</code>.I am using vs 2005.In my machine there is vs2005,vs2008,vs2010.When I am opening vs 2005,I can see Ajax Extention in toolbar(There is only basic 5 control like timer,updatepannel,progress),when I am trying drag a update pannel from toolbox,code for assembly comes that <code>system.web.Extention</code> version 1.0 and same is in web config.Then where is a mistake.</p>
