[Zope] eTailer Error

[LARRY CHUON]

When I click on "Check Out", I receive the following error message.  Can someone shed some lights please?

 
  Zope Error

  Zope has encountered an error while publishing this resource. 

  KeyError

  Sorry, a Zope error occurred.

  Traceback (innermost last):
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/Publish.py, line 222, in publish_module
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/Publish.py, line 187, in publish
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/Zope/__init__.py, line 221, in zpublisher_exception_hook
      (Object: CatalogAware)
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/Publish.py, line 171, in publish
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/mapply.py, line 160, in mapply
      (Object: checkOut)
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/Publish.py, line 112, in call_object
      (Object: checkOut)
    File /usr/local/Zope-2.2.4-linux2-x86/Products/Etailer/Cart.py, line 35, in checkOut
      (Object: Traversable)
    File /usr/local/Zope-2.2.4-linux2-x86/lib/python/ZPublisher/HTTPRequest.py, line 810, in __getitem__
  KeyError: cart_items




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