[Zope] UnpickleableError with objects derived from Sync.Synchronized

[Alexei Ustyuzhaninov]

Hi!

I have objects in my product which shouldn't be accessed simultaneously 
by different threads. So I mixed their class in the Sync.Synchronized 
class as recommended in 
http://www.zope.org/Documentation/How-To/ThreadSafety. But now I can't 
even create the objects because of UnpickleableError:

Traceback (innermost last):
   File /usr/lib/zope/lib/python/ZPublisher/Publish.py, line 223, in 
publish_module
   File /usr/lib/zope/lib/python/ZPublisher/Publish.py, line 187, in publish
   File /usr/lib/zope/lib/python/Zope/__init__.py, line 226, in 
zpublisher_exception_hook
   File /usr/lib/zope/lib/python/ZPublisher/Publish.py, line 175, in publish
   File /usr/lib/zope/lib/python/Zope/__init__.py, line 240, in commit
   File /usr/lib/zope/lib/python/ZODB/Transaction.py, line 302, in commit
   File /usr/lib/zope/lib/python/ZODB/Connection.py, line 418, in commit
     (Info: (('Products.Tap3Editor.tap3editor', 'tap3editor'), 
'\x00\x00\x00\x00\x00\x00j\x08', ''))
UnpickleableError: (see above)

I use zope 2.4.2 for linux from debian binary distribution.

So could someone explain what's the problem here?

-- 
Best regards,
Alexei