You have to read the REI documentation very carefully on this one. The method GetAllClasses says:
This function returns all classes belonging to all categories in the model
The key word here is "categories". The only classes in Rose that have parent classes are nested classes. Since they do not belong to a category, they are not returned by aModel.GetAllClasses(). The code below will get to the nested classes.
If your definition of ParentClass is other than class containing a nested class, then there are probably other ways to get what you are looking for.
Sub Main
Dim cc As ClassCollection
Set cc = RoseApp.CurrentModel.GetAllClasses()
Viewport.open
For i = 1 To cc.Count
Print cc.GetAt(i).name
If cc.GetAt(i).GetNestedClasses.Count > 0 Then
For j = 1 To cc.GetAt(i).GetNestedClasses.Count
Print Tab(5); cc.GetAt(i).GetNestedClasses.GetAt(j).Name
If Not cc.GetAt(i).GetNestedClasses.GetAt(j).ParentClass Is Nothing Then
Print Tab (10); cc.GetAt(i).GetNestedClasses.GetAt(j).ParentClass.Name
End If
Next j
End If
Next i
End Sub
