title: Implicit conversion is accepted in one of my VS2012 solutions but not in the other. Why?
body: <p>I have two C# solutions in VS 2012.</p>
  
  <p>The following explicit conversion works in both solutions:</p>
  
  <pre><code>Excel.Range rng = (Excel.Range)Date.DataRange.Cells[1];
  </code></pre>
  
  <p>The following implicit conversion works in one of the solution but generates an error in the other solution:</p>
  
  <pre><code>Excel.Range rng = Date.DataRange.Cells[1];
  </code></pre>
  
  <p>What might be the reason why the implicit conversion works in one of the projects but not the other?</p>
  
  <p>EDIT: The error message that I get is <code>'object' does not contain a definition for 'Group' and no extension method 'Group' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)</code></p>