title: c# VS 2015 Package recently getting null by GetService and Dte(2).GetObject without changes in the code
body: <p>I'm using the following properties in a VS (2015) Package:</p>
  
  <pre><code>    public DTE Dte
      {
          get
          {
              return GetService(typeof(DTE)) as DTE;
          }
      }
  
      public ITeamFoundationContextManager TeamExplorer
      {
          get
          {
              return GetService(typeof(ITeamFoundationContextManager)) as ITeamFoundationContextManager;
          }
      }
  
      public DocumentService DocService
      {
          get
          {
              return Dte.GetObject("Microsoft.VisualStudio.TeamFoundation.WorkItemTracking.DocumentService")
              as DocumentService;
          }
      }
  </code></pre>
  
  <p>The first one (Dte) seems to work fine and returns a DTE object.
  The second (TeamExplorer) does always return <strong>null</strong>,
  just like the third property (DocService).</p>
  
  <p>The problem is, that I (and no other) did not check-in any changes since the last release build. The last release build still works on installation, but if I rebuild it, there is the <strong>null</strong>-value issue.</p>
  
  <p>The problem also appears on a co-workers machine.
  My Extensibility Tools version is: <strong>1.10.183</strong></p>