[Zope] _delObject errors

[seb bacon]

When I try to call self._delObject('foo') from my Product, it seems to work, but I get an error logged:

  AttributeError: 'string' object has no attribute 'manage_beforeDelete'

The offending line is in ObjectManager.py:

 def _delObject(self, id, dp=1):
        object=self._getOb(id)
        try:
            object.manage_beforeDelete(object, self)

So, it would appear that self.getOb('foo') returns a string rather than whatever it's expecting.  I presume this is because the object I'm deleting doesn't have some requisite base class to make it zope-manageable.  It's a ZClass which has ZObject as its only base class.

Am I missing something?

Cheers,

seb