How do I resize a comment box in VB?

When I record a macro I get :

Range("C9").Select
Range("C9").AddComment
Range("C9").Comment.Visible = False
Range("C9").Comment.Text Text:="Bladiblabla"
Selection.ShapeRange.ScaleHeight 0.3, msoFalse, msoScaleFromTopLeft
Selection.ShapeRange.ScaleWidth 0.1, msoFalse, msoScaleFromTopLeft

Running this code results in :

Runtime error '438':
Object doesn't support this property or method

Anyone any idea?

Thanks in advance.