Changing the class of a v.i.

Hi.

I'm trying to change the class of one instance variable of an object persistend in a MagmaCollection. Schematically, what I'm doing is

open a session retrive the object begin transaction change the classs (using #primitiveChangeClassTo: commit transaction close session

open session retrieve the object check the class . FAILS!.

I tried removing the object from the collection, and readding it, but it failed too. Could anybody tell me is there is a special thing I must do to achieve this need?

I'm sending a test with an example and some sample classes.

Thanks in advance.