cxDBTreeList 如何动态添加汇总项？(100)

cxDBTreeList版本是5.48。在 Columns->Summary-> FooterSummaryItems 或 GroupFooterSummaryItems下静态添加没问题。我的代码如下：with cxDBTreeList1.ColumnByName('xxx').Summary.FooterSummaryItems.Add as TcxTreeListSummaryItem dobegin Kind:=skCount; Format:='笔数:#,0';end;编译能通过，但是运行总在Add的时候出现AV错误。请指教！

with cxDBTreeList1.ColumnByName('xxx').Summary.FooterSummaryItems.Add as TcxTreeListSummaryItem do===>with cxDBTreeList1.Columns.Summary.FooterSummaryItems.Add as TcxTreeListSummaryItem do

接受答案了.