openldap addressbook problem==nubie here

[Muhammad Reza <reza@infosaham.com>]

dear list,

i have problem to create addressbook directory with openldap-2.0.27 at 
RH-9.0
this my slapd.conf
include         /etc/openldap/schema/core.schema
include         /etc/openldap/schema/cosine.schema
include         /etc/openldap/schema/inetorgperson.schema
#pidfile        //var/run/slapd.pid
#argsfile       //var/run/slapd.args
database        ldbm
suffix          "dc=infosaham, dc=com"
rootdn          "dc=infosaham, dc=com"
rootpw          secret
index            objectClass   eq

and my directory.ldif

dn:     dc=infosaham, dc=com
objectClass:    top
objectClass:    dcObject
objectClass:    organization
dc:     infosaham
o:      InfoSaham Inc.

dn:     ou=addressbook, dc=infosaham ,dc=com
objectClass:    top
objectClass:    organizationalUnit
ou:     addressbook

the error when i try to add ldif file
#ldapadd -D  'dc=infosaham, dc=com' -f directory.ldif -W -x

ldap error with info :DN invalid Syntax

how my remedy ? any kkind of help will apreciate

regards
reza