title: OpenStreamForWriteAsync Doesn't finish
body: <p>I am trying to save a serialised object to a file. When I call the <code>OpenStreamForWriteAsync</code> method the UI locks up and the process never seems to end. Not sure what I am doing wrong here.</p>
  
  <pre><code>            public async Task&lt;string&gt; Save(string fileName)
      {
          MemoryStream ms = new MemoryStream();
          var serializer = new DataContractSerializer(typeof(Settings));
  
          serializer.WriteObject(ms, this);
  
          ms.Position = 0;
  
          try
          {
              using (var fms = await ApplicationData.Current.LocalFolder.OpenStreamForWriteAsync(fileName, CreationCollisionOption.ReplaceExisting))
              {
                  serializer.WriteObject(fms, this);
                  return "Saved successfully";
              }
          }
          catch
          {
              return "Could not save.";
          }
  
      }
  </code></pre>
  
  <p>This is my first question on StackOverflow, but have been a long time learner. Any help appreciated.</p>