If you use the http://download.zope.org/ppix or http://download.zope.org/simple indexes and try to get zope.app.authentication 3.4.3 (the newest), you will get a 404 error. Looking at PyPI and the zope.org index, it is evident why. http://pypi.python.org/pypi/zope.app.authentication/3.4.3 only lists one release, the source release http://download.zope.org/simple/zope.app.authentication/ lists 3.4.3 eggs as well. I strongly suspect that someone uploaded the zope.app.authentication eggs to PyPI; the zope.org index saw them and recorded them; and then someone removed the eggs from PyPI. It would be great if someone could re-upload the eggs to PyPI. More importantly, this is a reminder to please not remove eggs. The behavior or download.zope.org/simple is reasonable. Removing eggs isn't. :-) Thanks Gary