title: DataReader.GetFieldType returned null
body: <p>In my db table Layout, there's one column whose type is <code>hierarchyid</code> (column index=4).
  When trying to set-up new environment (a virtual web-server, created from XEN server), then running the site, I've met with this issue:</p>
  
  <blockquote>
    <p>Exception message: DataReader.GetFieldType(4) returned null. 
    Exception data: System.Collections.ListDictionaryInternal</p>
  </blockquote>
  
  <p>I've made some search and found out there are already some topic on it (such as on <a href="http://social.msdn.microsoft.com/forums/en-US/sqlnetfx/thread/eae17407-2910-455c-92eb-8c28e5dabbc5">MSDN</a>).</p>
  
  <p>But even when I added the <code>C:\Program Files\Microsoft SQL Server\100\SDK\Assemblies\Microsoft.SqlServer.Types.dll</code> library, it seems like db type in structure <code>SqlHierarchyId</code> doesn't get recognized. </p>
  
  <blockquote>
    <p>"Exception at DataReader.GetFieldType(4) returned null" is still thrown out.</p>
  </blockquote>
  
  <p>Note: The issue will be solved if I made installation of C# package in VS2010 onto the environment (Windows Server 2008 RC2), but my boss didn't accept that, because this is purely a simple web-server.</p>