can't understand the following error : ClassInfo that cannot be casted to LinkInfo

Hi there !

I have a problem that is very hard for me to understand.

I meet the following error :

wt.introspection.ClassInfo cannot be cast to wt.introspection.LinkInfo

How can this kind of error can comes from ?

Do it comes from links between java class or another cause ?

In my code, the problem is caused by the saving of an instance :

PersistenceHelper.manager.delete(instance);

but I delete it after saving it, It tell it in case this is a problem. I save the instance with that code :

PersistenceHelper.manager.save(instance);

here is the delete method :

public Persistable delete(Persistable paramPersistable)

  throws WTException

{

  WTHashSet localWTHashSet = new WTHashSet();

  localWTHashSet.add(paramPersistable);

  delete(localWTHashSet);

  return paramPersistable;

}

thank you !