title: Conditional Operator with DateTime? won't compile
body: <p>Can anyone tell me why this won't compile?</p>
  
  <pre><code>DateTime? completedDT;
  bool completed = false;
  completedDT= completed ? DateTime.Now : null;
  </code></pre>
  
  <p>I would have thought that as it was writing to a nullable object (<code>DateTime?</code>) the use of null would be acceptable. Instead I get this error:</p>
  
  <blockquote>
    <p>Error  19  Type of conditional expression cannot be determined because there is no implicit conversion between 'System.DateTime' and 'null'</p>
  </blockquote>