Are you sure you've specified correct CA?
Can you try running this command: LDAPTLS_CACERT=your_ldap_ca_cert.crt ldapsearch -H ldaps://@HOST@ -x -D '@USERDN@' -w '@USERPW@' -b '@BASEDN@'
If it fail then most probably you have incorrect CA certificate. If it succeed, please open bug in bugzilla with logs of setup tool if possible.
Oh I'm sorry, that was actually a certificate problem... With the right certificate, I can now join the LDAP provider. However, I can't login with any user...But with ldapsearch I can find those users with uid=user I used ovirt-engine-extensions-tool aaa login-user --profile=xxx --user-name=xxx and I realize now what is the problem : the available namespaces shows the wrong dn. It should be instead one level above (or it will not possible to find the users) Any idea how I can change that in the configuration ?