Error during ldapadd

["Gar Nelson" <Gar.Nelson@noaa.gov>]

I'm using openldap-2.0.18 from source on a RH 7.1 system.

The references I've been using are:
OpenLDAP 2.0 Administrator's Guide
LDAP Implementation HOWTO - authentication using pam_ldap and nss_ldap
You Can Get There From Here, pt 3 and pt 4 (Linux Journal SysAdmin 
section, Sept 2001, Oct 2001)

My goal is a secure 'nis' using OpenLDAP.

Using the command: 
ldapadd -f example.ldif -x -D "cn=xxxxx,dc=ohx,dc=noaa,dc=gov" -W

I get:
adding new entry "dc=ohx,dc=noaa,dc=gov"
ldap_add: already exists

The directory /usr/local/var/openldap-ldbm is empty

example.ldif
dn:dc=ohx, dc=noaa, dc=gov
objectclass: top
objectclass: organizationalUnit

dn:ou=groups, dc=ohx, dc=noaa, dc=gov
objectclass: top
objectclass: organizationalUnit
ou: groups

dn:ou=people, dc=ohx, dc=noaa, dc=gov
objectclass: top
objectclass: organizationalUnit
ou: people

dn: cn=Gar Nelson, ou=people, dc=ohx, dc=noaa, dc=gov
cn: Gar Nelson
sn: Nelson
objectclass: top
objectclass: person
objectclass: posixAccount
objectclass: shadowAccount
objectclass: organizationalPerson
objectclass: inetOrgPerson
uid:nelson
userpassword:xxxxxxx
uidnumber:1002
gidnumber:100
gecos:Gar Nelson
loginShell:/bin/bash
homeDirectory: /home/gnelson
shadowLastChange:10877
shadowMin: 0
shadowMax: 999999
shadowWarning: 7
shadowInactive: -1
shadowExpire: -1
shadowFlag: 0
mail: gar.nelson@noaa.gov
telephoneNumber: xxx-xxx-xxxx
givenname: Gar
surname: Nelson

So what have I got wrong that is keeping the database from getting 
populated?

Gar