OK, the reason you're getting that exception is that the Northwind connection is the active connection.  The Database Connection option in the StrataFrame menu is not used for your application's connections.  The only connection that should be listed within the Database Connections is the StrataFrame connection.  Your application's connection string is configured through the SetDataSources() method of the AppMain.vb (or program.cs file).  So, the StrataFrame design-time components were trying to use the Northwind connection to find the StrataFrame tables (which is, of course, not going to work ).  So, delete that Northwind connection and configure it within the SetDataSource() and set the active StrataFrame Database Connection as the correct one within the Database Connections dialog.  The BOMapper will come back to life.

That did it!  Thanks!

Excellent glad to hear it.