casting an object from a wpf datagridrow

I have a wpf datagrid that and am trying to cast a datagrid.SelectedItem to a custom object. Getting the error "Unable to cast object of type 'System.Data.DataRowView' to type 'CarrierRecord'." when this line "set carrierRecord to DG_CellCarriers::SelectedItem as type CarrierRecord" is executed. Works just fine in c#.  Am I missing something basic here? My datagrid is bound to a datatable.