This post was related to the RadGridView, so I moved it to the GridView section. It won't let me delete this post.
http://www.telerik.com/community/forums/silverlight/gridview/selectionchangedcommand-and-button-click-events-in-radgridview-with-childtabledefinitions.aspx
http://www.telerik.com/community/forums/silverlight/gridview/selectionchangedcommand-and-button-click-events-in-radgridview-with-childtabledefinitions.aspx