Hey John,
I got the same issue. I ran the command you suggested and here is the output:
[root@XX12 zimbra]# sudo /opt/zimbra/openldap-2.3.34/libexec/slapd -d7 -l LOCAL0 -4 -u zimbra -h dap://mail.mpseast.com:389 -f /opt/zimbra/conf/slapd.conf
@(#) $OpenLDAP: slapd 2.3.34 (Mar 28 2007 13:42:25) $
build@build.liquidsys.com:/home/build/p4/main/ThirdParty/openldap/openldap-2.3.34/servers/slapd
daemon_init: dap://mail.mpseast.com:389
daemon_init: listen on dap://mail.mpseast.com:389
daemon_init: 1 listeners to open...
ldap_url_parse_ext(dap://mail.mpseast.com:389)
daemon: listen URL "dap://mail.mpseast.com:389" parse error=3
slapd stopped.
connections_destroy: nothing to destroy.
[root@XX12 zimbra]#
Any ideas?