Sheet activate method in beforesave event

Hi

I would like to know why activate method in beforesave event does not
work. Could you help me?
(If you know, please let me know url of MSDN page explaining this
restriction.)

-----------ThisWorkbook Module--------------
Sub test()
ActiveWorkbook.Save
End Sub
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, _
Cancel As Boolean)
Sheets("sheet2").Activate
End Sub
----------------------------------------------------

Case 1 When save by file menu or Ctrl+s
"Sheets("sheet2").Activate" will work.

Case 2 When run test procedure
"Sheets("sheet2").Activate" will not work.

Thanks to all,
bdg

I forgot to write.
Both case 1 and 2, sheet1 is active at first.