title: The '?' character cannot be used here
body: <p>With these variables:</p>
  
  <pre><code>Dim d1 As Date? = Nothing
  Dim d2 As DateTime? = Nothing
  Dim i1 As Integer? = Nothing
  Dim i2 As Int32? = Nothing
  </code></pre>
  
  <p>Why am I allowed to do this?:</p>
  
  <pre><code>Dim flag1 As Boolean = Date?.Equals(d1, d2)
  Dim flag2 As Boolean = Integer?.Equals(i1, i2)
  </code></pre>
  
  <p>...but not allowed to do this?:</p>
  
  <pre><code>Dim flag3 As Boolean = DateTime?.Equals(d2, d1)
  Dim flag4 As Boolean = Int32?.Equals(i2, i1) 
  </code></pre>
  
  <p>The last code will fail with an error saying:</p>
  
  <blockquote>
    <p><em>The '?' character cannot be used here.</em></p>
  </blockquote>