title: System.Linq namespace missing even with reference to System.Core.Dll
body: <p>When I open up a Asp Net web site of mine in Visual Studio 2010 the properties say "Target Framework 3.5", however when I try to using the Linq namespace the compiler complains about it.</p>
  
  <p>"The type or namespace name 'var' could not be found (are you missing a using directive or an assembly reference?)"</p>
  
  <p>"The type or namespace name 'Linq' does not exist in the namespace 'System' (are you missing an assembly reference?)"</p>
  
  <p>I manually referenced some dll's to fix my problem, but still no success.</p>
  
  <pre><code>&lt;add assembly="System.Core, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
  &lt;add assembly="System.Data.DataSetExtensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
  &lt;add assembly="System.Data.Linq, Version=3.5.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
  </code></pre>
  
  <p>Help? :-)</p>