Shapes do not have a Caption. Maybe you have found Windows code using ActivX shapes. Macs do not support this
With a shape you would need something like
Code:
Sub add10()
Dim osld As Slide
Dim oshp As Shape
Set osld = SlideShowWindows(1).View.Slide
Set oshp = osld.Shapes("ascore")
If oshp.TextFrame.TextRange = "" Then oshp.TextFrame.TextRange = "0"
oshp.TextFrame.TextRange = oshp.TextFrame.TextRange + 10
End Sub