Using Delphi 7 + Office2010, programming operation PPT:

PptApp:=CreateOleObject (' PowerPoint. Application);//create PPT application
PptApp. Presentations. Open (' test. PPTX ');

Found two problems:
1, powerpoint window can't hide
2, perform pptApp. Quit; Cannot close powerpoint window,

I do not know what reason be? And similar code, Word, Excel all normal,