title: The type or namespace name 'Linq' does not exist in the namespace 'System'
body: <p>I have a wcf service hosted in a website in IIS and I seem to have this issue.
  In my web.config I have this:</p>
  
  <pre><code>&lt;system.web&gt;
          &lt;compilation&gt;
              &lt;assemblies&gt;
                  &lt;add assembly="System.Core, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System.Data.Linq, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System.Web, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/&gt;
                  &lt;add assembly="System.Web.Extensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/&gt;
                  &lt;add assembly="System.Data.DataSetExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;
                  &lt;add assembly="System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089"/&gt;&lt;/assemblies&gt;
          &lt;/compilation&gt;
      &lt;/system.web&gt;
  </code></pre>
  
  <p>All projects in the solution target framework 4.0.</p>
  
  <p>LE: I get the error when I try to import System.Linq;</p>
  
  <pre><code> using System.Linq;
  </code></pre>