hi, every one I'm a novice to zope. when I follow the example of zoopBook2.7 (http://www.plope.com/Books/2_7Edition/CustomZopeObjects.stx#2-47), I failed in adding ZClass instance. And the errlog is below. Can someone tell me what's wrong or how sould I to fix it or where to find the answer. Thanks. by nienfeng Exception Value default __new__ takes no parameters Traceback (innermost last): * Module ZPublisher.Publish, line 121, in publish * Module Zope2.App.startup, line 240, in commit * Module transaction._manager, line 96, in commit * Module Products.CPSCompat.PatchZODBTransaction, line 175, in commit * Module transaction._transaction, line 433, in _commitResources * Module ZODB.Connection, line 484, in commit * Module ZODB.Connection, line 526, in _commit * Module ZODB.Connection, line 553, in _store_objects * Module ZODB.serialize, line 407, in serialize * Module ZODB.serialize, line 416, in _dump * Module copy_reg, line 70, in _reduce_ex TypeError: default __new__ takes no parameters