iPrism lookups to Open Directory

We're testing an iPrism appliance (content filter) from St Bernard Software. While we have several other systems doing ldap lookups to OD, we cannot get the iPrism to connect to OD. Our OD master is 10.4.6, clear text passwords allowed, all UAM's enabled. It's not a context typo, because we can browse our ldap with various tools, such as LDAP browser. When attempting an anonymous bind from the iPrism, it returns a non-descript protocol error, no ldap log entries on the OD master. While St Bernard software claims to have many clients doing this, their tech support is stumped. We even set up a brand new OD master, all default configs - the iPrism throws the same protocol error. Any ideas? Could it be that OD is LDAPv3 while the iPrism may only handle LDAPv2?