In Zope 2.4.1 (at least), it is impossible in ZMI to test a Python Script, if the Script returns 0 (integer zero). Such scripts run fine when used, but they can't be tested in the ZMI. Scripts usually IMHO use 0 to indicate "false", and 1 to indicate "true". ZMI testing works fine if string values "0" and "1" are returned. Unfortunately, both "1" and "0" are considered "true" in python. Therefore the only workaround is to return empty string to indicate "false". -- Milos Prudek