Web Application not getting reference to ASP namespace

I've got code I've inherited from a vendor that's ju开发者_JAVA技巧st their SVN dump to the inetpub folder and I wanted to pull the files into our source control as a file based web application in visual studio 2008.

The project was originally a web site project and I'm trying to convert it to a web application project.

However, the compiler complains about the ASP namespace not being referenced. Since that namespace is dynamically created, how do I get around this?

UPDATE: Sorry for leaving this for so long, but I thought this image would context:

alt text http://img638.imageshack.us/img638/8431/asp.png

Do you mean that you're getting errors when you try and request the pages in the browser stating that it can't find things like ?

In which case, make sure that in your web.config in the <system.web> block you have something like:

<pages>
  <controls>
    <add tagPrefix="asp" namespace="System.Web.UI" 
         assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
    <add tagPrefix="asp" namespace="System.Web.UI.WebControls"
         assembly="System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
  </controls>
</pages>

It's highly like that the other vendor had included these settings futher down the .config stack (say in the framework web.config as has been done in ASP.NET 4)