How do I use VC++6.0 to protect a excel file to readonly

[gowinder]

I use VC++6.0 to create a temp excel file, and I don't want other use
to modify it, I use _Workbook.ChangeFileAccess to set readonly, but i
cannot help, a exception throw out, the message is "cannot fin
member", when I invoke ChageFileAccess function, the code is lik
this:

COleVariant vtOptional((long)DISP_E_PARAMNOTFOUND,
VT_ERROR),vtTrue((short)TRUE),vtFalse((short)FALSE);
_Application *ExcelApp = new _Application;

ExcelApp->CreateDispatch("excel.application");



//ÉèÖÃΪÏÔʾ
ExcelApp->SetVisible(TRUE);
//µÃµ½WorkBooks
Workbooks ExcelBook=ExcelApp->GetWorkbooks();



Sheets ExcelSheet=ExcelBook.Add(vtOptional);
_Workbook workBook;
_Worksheet workSheet;
Range range;
workBook.AttachDispatch(ExcelApp->GetApplication());

ExcelSheet=workBook.GetSheets();

////////////////////////////////////////////
workSheet=ExcelSheet.GetItem(COleVariant((short)1));
workSheet.Activate();

can anyone help me? Thanks

 

[gowinder]

Please help me