[Zope] Error creating Zclass in 2.6.1b1

I'm getting this error creating ZClasses in 2.6.1b1: <!-- <p>Traceback (innermost last): <ul> <li> Module ZPublisher.Publish, line 98, in publish</li> <li> Module ZPublisher.mapply, line 88, in mapply</li> <li> Module ZPublisher.Publish, line 39, in call_object</li> <li> Module ZClasses.ZClass, line 149, in manage_addZClass</li> <li> Module OFS.ObjectManager, line 272, in _setObject</li> <li> Module ZClasses.ZClass, line 419, in manage_afterAdd</li> <li> Module ZClasses.ZClass, line 372, in _register</li> <li> Module ZODB.Connection, line 533, in setstate</li> </ul>ImportError: No module named *8mbfp93SEeQ8XFA9crir6A== </p> --> Any ideas?