Text file with actual copy of complete error messages attached.

With my XamDataTree displayed, I am monitoring the Visual Studio Output window.  In the Output window I'm seeing 'System.Windows.Data Error:' periodically appear.  The messages appear sporadically but seem to be triggered by movement  of the scroll bar.

The essense of each message is:

'site_name' property not found on 'SecurityApp.CAPs.Model.Company'

I don't understand why I'm seeing these messages because 'site_name' is definately not a property of Company.  It's a property of Site of which Company contaings a collection.  My NodeLayout clearly specifies 'site_name' as a property of Site.  The node layout specifications are also shown in the attached text file.  I would have shown the code here except the automatic formatting plays havoc with code.  (Is there a way to enter code directly in a post?)

Please help me understand this.