'' is not a valid integer value! 错误提示

if MessageDlg(' 是否保存 ？', mtInformation, [mbYes, mbNo], 0) = mrYes then
    begin
      DataT := formatdatetime('yymmdd',date);
      ProNum := DataT+RandToChar;  { 窗口产生时数据自动保存}
   DBChart1.SaveToMetafile(GetExePath +'CollePic\P'+ProNum+'.wmf');      //  CollePic\
   DB_DBChart2.SaveToMetafile(GetExePath +'CollePic\DB'+ProNum+'.wmf');  // CollePic\    // 将 Access 数据导入到 Excel 中
      ADOConnectionAccessToExcel.ConnectionString:='Provider=Microsoft.Jet.OLEDB.4.0;Password="";Data Source='+
      GetExePath +'Database\wava.mdb;Persist Security Info=True';
      query1.close;
      query1.sql.clear;
      query1.sql.add('select * from wavetable');
      query1.open;      
   if query1.recordcount <>0 then
        begin
          ADOConnectionAccessToExcel.execute('Select * Into [Excel 8.0;DATABASE='+GetExePath +'ColleExporttoExcel\'+ProNum+'.XLS].[数据采集] FROM [wavetable]');     //导为 *.xls
          ADOConnectionAccessToExcel.close;
        end;
   { 结束 窗口产生时数据自动保存}
      if not Assigned(ColleInfoForm1) then
        begin
          ColleInfoForm1:=TColleInfoForm1.create(Application);
          ColleInfoForm1.showmodal;
          freeandnil(ColleInfoForm1);
        end;
    end
else
    begin    
       //存储清除
        query1.close;
        query1.sql.clear;
        query1.sql.add('select * from wavetable');
        query1.open;
        if query1.recordcount<>0 then
              begin
                query1.close;
                query1.sql.clear;
                query1.sql.add('delete from wavetable');
                query1.ExecSQL;
                query1.close;
                //==================================================================
               // Application.MessageBox('数据成功删除！','提示信息',mb_ok);
                //------------------------------------------------------------------
                SeriesTimer.Enabled:=False;   //时钟置为 0
                EditColleTime.Enabled:=true;
                //EditColleTime.text:='0';     
                EditTimeX.text:='0';           //采集源置 0
                EditPtY.text:='0';
                EditPrY.text:='0';
                EditAx.text:='0';
                //------------------------------------------------------------------
      CollectionQuery.Close;
      CollectionQuery.Open;
              end
            else
              begin
                exit;
              end;
             //存储清除
   
    end;注释： 其中参数ProNum：类型是string 
调试错误指示在这行： if MessageDlg(' 是否保存 ？', mtInformation, [mbYes, mbNo], 0) = mrYes then
错误提示是： '' is not a valid integer value!  
不知什么原因？希望赐教~`