Quoting Jaap Winius <jwinius@umrk.nl>:
... and I've been able to get it to work on Debian squeeze using 2.4.23 (with Pierangelo's 2010-04-29 patch) and clear-text passwords, ...
Sorry, that's apparently not the case. Now I'm getting the same error with the simple bind configuration:
adding new entry "cn=ccolumbus,ou=groups,dc=example,dc=com" ldap_add: Strong(er) authentication required (8)
There must be something else going on... Cheers, Jaap