unable to load back-perl module

Hi, I'm unable to load the back-perl backend module, I get "lt_dlopenext failed: (back_perl.la) file not found" But back_perl.la is there though, and I can load other modules without problem (back_hdb.la, back_sql.la, ...) Any idea what's going on ? My slapd.conf : # Load dynamic backend modules: modulepath /usr/local/libexec/openldap moduleload back_hdb.la moduleload back_sql.la moduleload back_perl.la If I comment the last line, slapd starts without problem. The error message : root@ldap:~# /usr/local/libexec/slapd -u openldap -g openldap -d 256 514dbea0 @(#) $OpenLDAP: slapd 2.X (Feb 3 2013 19:41:33) $ root@ldap:/tmp/openldap-a98eb28/servers/slapd 514dbea0 lt_dlopenext failed: (back_perl.la) file not found 514dbea0 slapd stopped. 514dbea0 connections_destroy: nothing to destroy. It doesn't find back_perl.la, but the file exists though, with the same right as the other backend modules: root@ldap:/usr/local/libexec/openldap# ls -la -rwxr-xr-x 1 root staff 987 Feb 3 19:43 back_hdb.la -rwxr-xr-x 1 root staff 1026 Feb 3 19:43 back_perl.la -rwxr-xr-x 1 root staff 991 Feb 3 19:43 back_sql.la I'm using OpenLDAP 2.4.33 on Debian 6.0.4 Ben.