TDBCtrlGrid如何使用?

要使每条记录(面板)显示的照片来自该记录中的某个字段,为什么不行?

procedure TfrmConfluence.DBCtrlGrid1PaintPanel(DBCtrlGrid: TDBCtrlGrid;  Index: Integer);var  S: String;begin  try    Image1.Picture:= nil;    S:= DBCtrlGrid.DataSource.DataSet.FieldByName('Picture').AsString;    if FileExists(S) then      Image1.Picture.LoadFromFile(S);  except    //  end;end;