Error or no error... this is the question!!!

[isabelle]

If the name of the librairy is "a" and the class on that librairy is "b", I use the CreateObject like this:
Private obj as Object
Set obj = CreateObject ("a.b")

Is it correct?
If not, can you tell me the good way?
If yes, can you tell me why I got a 429 run-time error every time I tried?

Thanks a lot for all help you can give me,
Isabelle