Delphi XE2 VCL application gives access violation when calling EXCEL properties in iterations such as for-loops

Question

Possible Duplicate:
Is COM broken in XE2, and how might I work around it?

The VCL applications referred to call EXCEL via "early binding" as instructed in Deborah Pate's Automating Excel Pages(http://www.djpate.freeserve.co.uk/AutoExcl.htm). Specifically, the applications modify the font of certain characters of two cells.

The application compiled using Delphi XE runs as expected. However, the application compiled using Delphi XE2 gives access violation in the second iteration of for-loop. I mean, if I do not use for-loop, and modify the two cells manually, the application runs as expected. I have no clue what the cause could be. Any help will be appreciated!

The EXCEL type library .pas files are generated by DXE and DXE2, respectively.

The source codes of the main unit are pasted below for your convenience. The whole directories are packaged into .zip files and can be downloaded here.

http://www.fileserve.com/file/HxyZw9w/TestExcelCharacters_1_DXE.zip

http://www.fileserve.com/file/pd8Q8qm/TestExcelCharacters_1_DXE2.zip

Source code in Delphi XE VCL application

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  ComObj, ActiveX, Excel_TLB;

procedure TForm1.FormCreate(Sender: TObject);
var
  lcid: integer;
  AppWasRunning: boolean;
  Result: HResult;
  Unknown: IUnknown;
  Excel: _Application;
  WBk: _Workbook;
  WS: _WorkSheet;

  l_RIdxStr, l_CIdxStr: string;
  l_CharStartIdx, l_CharLength: Integer;
  l_XlsSpinLine: string;

  I: Integer;
begin
  lcid := LOCALE_USER_DEFAULT;
  AppWasRunning := False;

  Result := GetActiveObject(CLASS_ExcelApplication, nil, Unknown);
  if (Result = MK_E_UNAVAILABLE) then
  begin
    Excel := CoExcelApplication.Create
  end
  else
  begin
    OleCheck(Result);
    OleCheck(Unknown.QueryInterface(_Application, Excel));
    AppWasRunning := True;
  end;
  Excel.Visible[lcid] := True;

  // Create empty Excel workbook
  WBk := Excel.Workbooks.Add(EmptyParam, LCID);

  WS := WBk.Worksheets.Item['Sheet1'] as _Worksheet;
  WS.Activate(LCID);

  WS.Range['D5', 'D5'].Value[xlRangeValueDefault] := 'Ru12.11256 Ru2-1.22587';
  WS.Range['D6', 'D6'].Value[xlRangeValueDefault] := 'Ru10.11256 Ru2-0.22587';
  WS.Range['D5', 'D5'].EntireColumn.AutoFit;

  for I := 0 to 1 do
  begin
    l_RIdxStr := 'D' + IntToStr(5 + I);
    l_CIdxStr := l_RIdxStr;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[1, 2].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[1, 2].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[3, 1].Font.Subscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[4, 7].Font.Superscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[11, 1].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[11, 1].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[12, 2].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[12, 2].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[14, 1].Font.Subscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[15, 8].Font.Superscript := True;
  end;
end;

end.

Source code in Delphi XE2 VCL application

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs;

type
  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

uses
  ComObj, ActiveX, Excel_TLB;

procedure TForm1.FormCreate(Sender: TObject);
var
  lcid: integer;
  AppWasRunning: boolean;
  Result: HResult;
  Unknown: IUnknown;
  Excel: _Application;
  WBk: _Workbook;
  WS: _WorkSheet;

  l_RIdxStr, l_CIdxStr: string;
  l_CharStartIdx, l_CharLength: Integer;
  l_XlsSpinLine: string;

  I: Integer;
begin
  lcid := LOCALE_USER_DEFAULT;
  AppWasRunning := False;

  Result := GetActiveObject(CLASS_ExcelApplication, nil, Unknown);
  if (Result = MK_E_UNAVAILABLE) then
  begin
    Excel := CoExcelApplication.Create
  end
  else
  begin
    OleCheck(Result);
    OleCheck(Unknown.QueryInterface(_Application, Excel));
    AppWasRunning := True;
  end;
  Excel.Visible[lcid] := True;

  // Create empty Excel workbook
  WBk := Excel.Workbooks.Add(EmptyParam, LCID);

  WS := WBk.Worksheets.Item['Sheet1'] as _Worksheet;
  WS.Activate(LCID);

  WS.Range['D5', 'D5'].Value[xlRangeValueDefault] := 'Ru12.11256 Ru2-1.22587';
  WS.Range['D6', 'D6'].Value[xlRangeValueDefault] := 'Ru10.11256 Ru2-0.22587';
  WS.Range['D5', 'D5'].EntireColumn.AutoFit;

  for I := 0 to 1 do
  begin
    l_RIdxStr := 'D' + IntToStr(5 + I);
    l_CIdxStr := l_RIdxStr;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[1, 2].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[1, 2].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[3, 1].Font.Subscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[4, 7].Font.Superscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[11, 1].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[11, 1].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[12, 2].Font.Superscript := False;
    WS.Range[l_RIdxStr, l_CIdxStr].Characters[12, 2].Font.Subscript := False;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[14, 1].Font.Subscript := True;

    WS.Range[l_RIdxStr, l_CIdxStr].Characters[15, 8].Font.Superscript := True;
  end;
end;

end.