slapo-unique

Hello. I have some strange issue with unique overlay. When I use these directives in slapd.conf overlay unique unique_uri ldap:///"o=company"?uid?sub I've been got error Starting slapd. Assertion failed: (pretty != NULL), function dnPrettyNormal, file dn.c, line 724. Abort trap

I'm using openldap v 2.4.9 and FreeBSD 7.0.

Without any dn information in unique_uri slapd starts fine. Let me know if you need any more information. I didn't find any information about this error anywhere. Please help. Thanks