Does PP count slides from zero?

Simple test code 
Sub T()
Dim X
X = slides(0) 'also try Shapes(0) I don't know PP rules
Set x = slides(0)
End sub
Where was the error, if any

I know VBA in general and VBA for Excel in particular, but all MS programs differ slightly in implementing VBA.

Show us your VBA code, I don't have PP on my computer, But I should understand the code.