cxGrid: How to get Footer Summary Values By Column

var

  AColumn: TcxGridDBColumn;

  ASummaryItem: TcxDataSummaryItem;

  AValue : String;

  ASummaryIndex: Integer;

begin

    AColumn := Dbtv.GetColumnByFieldName('Amount');

    if AColumn <> nil then

    begin

      ASummaryItem := Dbtv.DataController.Summary.FooterSummaryItems.GetDataItem(AColumn.Index, spFooter);

      if ASummaryItem <> nil then

      begin

        ASummaryIndex := ASummaryItem.Index;

        AValue := VarToStr(Dbtv.DataController.Summary.FooterSummaryValues[ASummaryIndex]);

      end;

    end;

end;