Using Framework reference, but can???t access DocumentClass

KP

I???m using Visual C# 2008 Express and I???m creating an Add=in button that will display the name of the map document when clicked.  The title property is available in the Document class using the interface IDocument.  I???m using the ESRI.ArcGIS.Framework reference, but the following code:

protected override void OnClick()         {                         IDocument doc = new DocumentClass();                ArcMap.Application.CurrentTool = null;         }

gives me the following error: ???the type or namespace name ???DocumentClass??? could not be found???.  I'm confused because this works with the MxDocumentClass and the ArcMapUI reference.  Any help would be greatly appreciated.

NeilClemmons_GISinc

The Document class is an abstract class (see the legend for the OMD).  Abstract classes cannot be instantiated.  The only classes you can create new instances of are listed in the help topic for IDocument (such as MxDocument).