Update to slave replica problem

[John Mok <jmok@attglobal.net>]

I hope someone could help me out.

SuSE Enterprise Linux Server 8
OpenLDAP 2.2.14

I have built two identical machines for LDAP replication testings, and 
compile OpenLDAP 2.2.14 from source as follows :-

env CPPFLAGS="-I/usr/local/include" LDFLAGS="-L/usr/local/lib" \
./configure --enable-wrappers --enable-crypt --enable-slurpd --with-tls

The replication from master to slave works fine, that the changes made 
to the master could be replicated to the slave server. The master server 
config. file has the following lines :-

replogfile    /var/ldap/slapd.replog
database bdb
suffix "dc=example,dc=com"
rootdn "cn=root,dc=example,dc=com"
rootpw secret
replica host=slave.example.com:389
       suffix="dc=example,dc=com"
       binddn="cn=replica,dc=example,dc=com"
       credentials=replica
       bindmethod=simple
       tls=yes

The slave server config. file has the following lines :-

database bdb
suffix "dc=example,dc=com"
rootdn "cn=replica,dc=example,dc=com"
rootpw replica
updatedn "cn=replica,dc=example,dc=com"
updateref ldap://master.example.com

However, when I tried to update the slave server,

>ldapadd -x -d -1 -h slave.example.com -D 
"cn=replica,dc=example,dc=com" -w replica -f newuser.ldif

it failed with the following error message :-

ldap_parse_result
ber_scanf fmt ({iaa) ber:
ber_dump: buf=0x080791a0 ptr=0x080791a3 end=0x080791da len=55
 0000:  69 35 0a 01 50 04 00 04  2e 6e 6f 20 73 74 72 75   i5..P....no 
stru 
 0010:  63 74 75 72 61 6c 4f 62  6a 65 63 74 43 6c 61 73   
cturalObjectClas 
 0020:  73 20 6f 70 65 72 61 74  69 6f 6e 61 6c 20 61 74   s 
operational at 
 0030:  74 72 69 62 75 74 65                               
tribute          
ber_scanf fmt (}) ber:
ber_dump: buf=0x080791a0 ptr=0x080791da end=0x080791da len=0
ldap_msgfree
ldap_perror
ldap_add: Internal (implementation specific) error (80)
   additional info: no structuralObjectClass operational attribute
ldap_free_connection

Is there anything I have done wrong?

Thanks a lot.

John