c# - WPF Print/ Print Preview Using DocumentViewer -

I am trying to get print preview to work but I do not see anything. I have a form called a screenshot form which uses document view here is the xaml code:

   & Lt; / Catalyst & gt; & Lt; /Style.Triggers> & Lt; / Style & gt; & Lt; /DocumentViewer.Resources> & Lt; / DocumentViewer & gt;  

The code behind it only returns a property property:

  public IDocumentPaginatorSource document {get_viewer.doco; } Set {_viewer.Document = value; }}  

I then have my visual model which I call to do a print preview to call screenshots. This is the place where I'm trapped window pops up properly, but it does not display any content.

  ScreenshotsForm oForm = New ScreenShotForm (); OForm.DataContext = This; OForm.ShowDialog ();  

I know I'm missing something, but I can not understand it. :?