New Install of VS 2012, old silverlight solution now gets exception: attachable property 'IsFieldGroup' was not found in type 'DataField'

I have a new machine (Win 8) and a new (clean) install of VS 2012 plus the SL SDK and VS Powertools 2012.  Now I'm attempting to run a Silverlight solution from my old computer which was running Win7 and VS 2010.  After spending several hours working through various issues in the solution and getting it to compile, when I run it, I get the following error on startup in the App.xaml.cs file.

$exception {System.Windows.Markup.XamlParseException: The attachable property 'IsFieldGroup' was not found in type 'DataField'. [Line: 11 Position: 44]
   at System.Windows.Application.LoadComponent(Object component, Uri resourceLocator)
   at Velocity_v02.App.InitializeComponent()
   at Velocity_v02.App..ctor()} System.Exception {System.Windows.Markup.XamlParseException}

The only reference to 'IsFieldGroup' is in a xaml style used in the assembly used to login with:

<Style x:Key="LoginDataFormStyle" TargetType="dataControls:DataForm">
<Grid dataControls:DataField.IsFieldGroup="True">
This code came from the login example of a Silverlight Business Application sample app many years ago.

Just to be safe, I've updated my references to:

System.Windows.Controls.Data.DataForm.Toolkit

and System.Windows.Controls.Data.Input

Any ideas on how to fix this error? 

Thanks!

moondaddy