When I look at the Password Hashes it gets quite obvious, what is wrong: the Hashes done by slappaswd for the Password supplied are 33 Bytes, those by LDAPAdmin are 65 Bytes (just 'wc'-ing, without {SSHA}-Prefix, same Password, both {SSHA}).
Please post examples, e.g. password 'test' (without quotes) generated by LDAPAdmin.
It's clear that 'slappasswd' is 'the one'
It's not clear since LDAPAdmin just could have chosen a longer salt.
See also: http://www.openldap.org/faq/data/cache/419.html
Ciao, Michael.