为什么不支持该属性？（VBA in PPT）

VBA代码如下(ppt)

Function GetShape(TargetSlide, Name As String)
    Dim shp
    For Each shp In TargetSlide.Shapes
        If shp.Name = Name Then
            Exit For
        End If
    Next shp
    GetShape = shp
End Function

这是结果

环境:Microsoft Office 2007