VBA not getting executed in .ppsm file

[VNJ]

Hello,

I have following VBA code in powerpoint 2007:

Sub OnSlideShowPageChange()
On Error GoTo ErrLog
    Dim i As Integer
    
    If Format(Date, "dd/mm/yyyy") = Format(CDate("21/5/2017")) Then
        'Run the Slide
       msgbox "Running"
    Else
         msgbox "Exiting"
        ActivePresentation.SlideShowWindow.View.Exit
    End If
    Exit Sub
    
ErrLog:
    MsgBox Err.Description
End Sub

i..e I want that this powerpoint .ppsm file run only on 21st May 2017. On other dates, it should exit. I save my pptm file and also saved in .ppsm format. When my pptm file is open, and I run .ppsm file from Windows Explorer, VBA code executes. But if I exit my .pptm file and then run .ppsm file from Windows Explorer, VBA code does not execute. Why?

Please Help....