TExcelApplication problem in Builder

I use TExcelApplication to connect to Excel and fill a workbook
After that I need to disconnect from Excel and leave the control to Windows.
But when I disconnect from Excel it also closes Excel window,which should stay alive till the user closes it.
Probably,the TExcelApplication component does not actually breaks the connection with Excel

Here's the code:

TExcelApplication *Excel;


TExcelWorksheet *ExcelWS = new TExcelWorksheet(this);
TExcelWorkbook *ExcelWB = new TExcelWorkbook(this);

Excel->Connect();
Excel->Workbooks->Add(EmptyParam,LOCALE_USER_DEFAULT);
Excel->set_SheetsInNewWorkbook(LOCALE_USER_DEFAULT, 1);
ExcelWB->ConnectTo(Excel->ActiveWorkbook);
ExcelWS->ConnectTo(Excel->ActiveSheet);

// Filling Workbook... OK

// Saving file... OK

// OK,now break all connections with Excel

Excel->set_Visible(LOCALE_USER_DEFAULT,xlSheetVisible) ;
Excel->set_UserControl(true);
ExcelWS->Disconnect();
ExcelWB->Disconnect();
delete ExcelWS;
delete ExcelWB;
Excel->Disconnect();


I tried a second method in which case I tried quitting Excel and then reopening the saved file using ShellExecute.But this time Excel does not show its client area.Besides ,inspite of the fact that I quit Excel (Excel->Quit() ),I still see Excel process in the processes list in the task manager.

I am stuck with this problem
Any help?
Thanks