Generally this means the snmp agent for ldap has exited.
It usually requires a restart of both slapd and the snmp agent.
As root
export SHORT=`uname -n | cut -f1 -d.` /opt/fedora-ds/slapd-$SHORT/stop-slapd /opt/fedora-ds/slapd-$SHORT/start-slapd /etc/init.d/snmpd restart