If you don't want any grouping in your grid at all (even programmatically), then you should set the ViewStyleBand to Multi or Single  (as opposed to OutlookGroupBy). 

I am trying to do this in the XAML.  I am using MVVM.   I will look at the windows init events.  If I have missed something as to the setup of the xml in XAML, please let me know.

Found it!  I guess it helped to post the message.    I guess I answered myself... should I be concerend?  :-)

it is an attribute on the XamDataGrid element:  

GroupByAreaLocation

="None"