title: MediaElement.NaturalDuration throws exception when querying TimeSpan.TotalSeconds
body: <p>I have a winforms form in which I use a MediaElement. Everything is working (more or less) perfectly. The only thing is, after loading a media file (mp3) accessing <code>NaturalDuration.TimeSpan.TotalSeconds</code> throws an exception</p>
  
  <blockquote>
    <p>InvalidOperatoinException: A TimeSpan property can not be returned for a duration value of automatic.</p>
  </blockquote>
  
  <p>(Translated from german by myself)</p>
  
  <p>How can I access the timespan property? There is no special setting used in all the examples I have found (ok, they seem to be WPF native...)</p>
  
  <p>I am using VisualStudio Express .Net 4, C# on Windows 7.</p>
  
  <p>Any hints?</p>