authz-regexp failures

Hi, I am facing some problems with authz-regexp configurations. These configurations run for ages on several systems. I only discovered recently, that some errors occured:

# ldapwhoami -Y EXTERNAL -H ldapi:/// SASL/EXTERNAL authentication started SASL username: gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth SASL SSF: 0 dn:gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth

The appropriate lines in slapd.conf:

authz-regexp "gidNumber=0+uidNumber=0,cn=peercred,cn=external,cn=auth" "cn=config"

There are still a few more authz-regexp rules that don't work anymore. Any ideas?

-Dieter