SlideShowNext will only run autmatically if you have it in a class module and declare it WithEvents and instigate it usually in a ppam AddIn.

If this makes no sense to you then you are biting off more than you can chew because it is not simple.

One answer is to use this instead
Sub OnSlideShowPageChange (SW as SlideShowWindow)

'do whatever
End Sub

This will work but can be unreliable after saving. You can help reliability by adding any activX item from the developer toolbox to slide 1 (no code needed). You can hide it using the Selection Pane.