Excel 自动输出保存问题 ？！

Question

var
  ExcelApplication1: TExcelApplication;
  ExcelWorksheet1: TExcelWorksheet;
  ExcelWorkbook1: TExcelWorkbook;
begin
  begin
    Try
        ExcelApplication1.Connect;
        Except
          MessageDlg('Excel may not be installed',mtError, [mbOk], 0);
          Abort;
        End;
        ExcelApplication1.Visible[0]:=True;
        ExcelApplication1.Caption:='天平数据记录';
        ExcelApplication1.Workbooks.Add(Null,0);
        ExcelWorkbook1.ConnectTo(ExcelApplication1.Workbooks[1]);
        ExcelWorksheet1.ConnectTo(ExcelWorkbook1.Worksheets[1] as _Worksheet);
        ExcelWorksheet1.Cells.Item[1,1].value := '实验日期';
        ExcelWorksheet1.Cells.Item[1,2].value := '班次';
        ExcelWorksheet1.Cells.Item[1,3].value := '操作员';
        ExcelWorksheet1.Cells.Item[1,4].value := '班长';
        ExcelWorksheet1.Cells.Item[1,5].value := '起始时间';
        ExcelWorksheet1.Cells.Item[1,6].value := '结束时间';
        ExcelWorksheet1.Cells.Item[1,7].value := '累计用料'; 
        
        
        ExcelWorksheet1.Columns.AutoFit;                
        ExcelWorksheet1.Disconnect;        
        ExcelWorkbook1.Disconnect;
        ExcelApplication1.Disconnect;
        ExcelWorksheet1.free;       
        ExcelWorkbook1.free;
        ExcelApplication1.free;
        ExcelApplication1.ActiveWorkbook.SaveAs('C:\1.xls',null,null,null,null,null,null,null,null,null,null,0);//这里出错！        
  end;   
end;   
请教高手，为什么保存总是出错！
我希望的结果是：数据自动输出保存到我指定的文件夹中！

Answer 1

var
 iRow,iBeginRow:integer;
         i,j:integer;
   SaveFileName:String;
begin
  SaveFileName:='D:\dd.xls';
  if  SaveFileName='' then
exit;
try
try
xlApp.ConnectKind:=ckNewInstance;
xlApp.Connect;
xlApp.Visible[0]:=True;
except
Application.MessageBox('没有安装Excel2000.','程序提示',mb_iconinformation);
exit;
end;
xlApp.WorkBooks.Add(EmptyParam,0);
xlBook.ConnectTo(xlApp.Workbooks[1]);
xlSheet.ConnectTo(xlBook.Worksheets[1] as _WorkSheet);
//打印和页面设置
xlSheet.PageSetup.Orientation:=xlLandscape;
xlSheet.PageSetup.LeftMargin := xlApp.InchesToPoints(0.354330708661417);
xlSheet.PageSetup.RightMargin := xlApp.InchesToPoints(0.354330708661417);
xlSheet.PageSetup.TopMargin := xlApp.InchesToPoints(0.511811023622047);
xlSheet.PageSetup.BottomMargin := xlApp.InchesToPoints(0.511811023622047);
xlSheet.PageSetup.HeaderMargin := xlApp.InchesToPoints(0.511811023622047);
xlSheet.PageSetup.FooterMargin := xlApp.InchesToPoints(0.275590551181102);
xlSheet.PageSetup.PrintTitleRows := '$1:$2';
//页眉页脚
// xlSheet.PageSetup.LeftFooter:= '日期：&D';
// xlSheet.PageSetup.RightFooter:='第 &P 页,共 &N 页'; //列宽
                for i := 1 to 13 do
                begin
                  xlSheet.Cells.Item[1,i].ColumnWidth:=8;
                end; //标题
xlSheet.Cells.Item[1,6]:=format('%d年【%s】逐日平均水位表',[2004, 'Name']);
xlSheet.Cells.Item[1,6].Font.Size:=18;
xlSheet.Cells.Item[1,6].Font.name:='黑体';
xlSheet.Cells.Item[1,6].Font.Bold:=True;
xlSheet.Range[xlSheet.Cells.Item[1,1],xlSheet.Cells.Item[1,13]].Merge(EmptyParam);
xlSheet.Cells.Item[1,1].HorizontalAlignment:=xlCenter;
xlSheet.Cells.Item[1,1].VerticalAlignment:=xlTop;
xlSheet.Cells.Item[1,1].RowHeight:=27;
                //副标题
xlSheet.Cells.Item[2,6]:='表内水位（冻结基面以上米数）'+ '米＝'+'基面以上米数';
xlSheet.Cells.Item[2,6].Font.Size:=9;
xlSheet.Cells.Item[2,6].Font.name:='黑体';
xlSheet.Range[xlSheet.Cells.Item[2,1],xlSheet.Cells.Item[2,13]].Merge(EmptyParam);
xlSheet.Cells.Item[2,1].HorizontalAlignment:=xlRight; //表头
iRow:=3;
xlSheet.Cells.Item[iRow,1]:='日\月';
xlSheet.Cells.Item[iRow,2]:='一月';
xlSheet.Cells.Item[iRow,3]:='二月';
xlSheet.Cells.Item[iRow,4]:='三月';
xlSheet.Cells.Item[iRow,5]:='四月';
xlSheet.Cells.Item[iRow,6]:='五月';
xlSheet.Cells.Item[iRow,7]:='六月';
xlSheet.Cells.Item[iRow,8]:='七月';
xlSheet.Cells.Item[iRow,9]:='八月';
xlSheet.Cells.Item[iRow,10]:='九月';
xlSheet.Cells.Item[iRow,11]:='十月';
xlSheet.Cells.Item[iRow,12]:='十一月';
xlSheet.Cells.Item[iRow,13]:='十二月';
xlSheet.Range[xlSheet.Cells.Item[iRow,1],xlSheet.Cells.Item[iRow,13]].Font.Bold:=True;
xlSheet.Range[xlSheet.Cells.Item[iRow,1],xlSheet.Cells.Item[iRow,13]].HorizontalAlignment:= xlCenter;
                iBeginRow:=iRow;
                  for j := 1 to 31  do
                  begin
                      xlSheet.Cells.Item[j+iRow,1]:=inttostr(j);
                      if (j mod 10 =0) and (j<>30) then
                      begin
                        iRow:=iRow+1;
                        xlSheet.Range[xlSheet.Cells.Item[j+iRow,1],xlSheet.Cells.Item[j+iRow,13]].Merge(EmptyParam);
                      end;
                  end;                //   填写页脚内容
                iRow:=iRow+32;
                iBeginRow:=iRow;
         xlSheet.Cells.Item[iRow,1]:='平均水位';
                for i :=1 to 12 do
                begin
                       xlSheet.Cells.Item[iRow,i+1]:='33';
                end;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='最高水位';
                for i :=1 to 12 do
                begin
                       xlSheet.Cells.Item[iRow,i+1]:='434';
                end;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='最高日期';
                for i :=1 to 12 do
                begin
                       xlSheet.Cells.Item[iRow,i+1]:='4234';
                end;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='最低水位';
                for i :=1 to 12 do
                begin
                       xlSheet.Cells.Item[iRow,i+1]:='455';
                end;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='最低日期';
                for i :=1 to 12 do
                begin
                       xlSheet.Cells.Item[iRow,i+1]:='4334';
                end;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='年统计';
                xlSheet.Range[xlSheet.Cells.Item[iRow,10],xlSheet.Cells.Item[iRow,13]].Merge(EmptyParam);
                xlSheet.Cells.Item[iRow,3].HorizontalAlignment:=xlCenter;
                iRow:=iRow+1;
         xlSheet.Cells.Item[iRow,1]:='附注';
                xlSheet.Range[xlSheet.Cells.Item[iRow,1],xlSheet.Cells.Item[iRow,13]].Merge(EmptyParam);
                iRow:=iRow+1; xlSheet.Range[xlSheet.Cells.Item[3,1],xlSheet.Cells.Item[iRow-1,13]].Borders.LineStyle := xlContinuous;
    xlSheet.SaveAs(SaveFileName);
finally
    xlApp.Disconnect;
    xlBook.Close;
    xlApp.Disconnect;
    xlApp.Quit;
    xlSheet.Disconnect;
    xlBook.Disconnect;
end;
    showmessage('保存数据文件：['+SaveFileName+ ']成功！')

Answer 2

有一点不理解，为什么我存
ExcelWorkbook1.saveas(Savefilename);
的时候就出错；
而存
ExcelWorksheet1.saveas(Savefilename);
的时候就可以呢；
按道理说应该是存ExcelWorkbook1才对啊，再说ExcelWorkbook1也支持SaveAs方法；

Answer 3

还有谁人能告知
ExcelWorkbook1.Disconnect;
ExcelWorkbook1.close;
ExcelWorkbook1.free;
三者的意义和区别关闭EXCEL的时候怎么释放
ExcelApplication1 
ExcelWorkbook1 
ExcelWorksheet1
以及三者的操作顺序；