New Post: New document ,in Powerpiont and Excel to call .Save(), is not same as in Word to show the "Save as"Dialog.

Hello,
ComAddin for Word, Powerpoint, Excel.
New document in Powerpiont and Excel to call .Save() ,the result is not like in word.

and my .Save Code:
in Powerpoint: "_powerpointApplication.ActivePresentation.Save()",
in Excel: "_excelApplication.ActiveWorkbook.Save() " ,
in Word: "_wordApplication.ActiveDocument.Save() " ,

In word, new document to .Save, will show "Save as" dialog, but not in Powerpoint and Excel.
Why? and how to do, let in Powerpoint and Excel to show the "Save as " dialog.