problems in memberof overlay

hi.

   I configured the function of 'memberof overlay' these days.
   At first I used the methods on the webpage of
http://www.openldap.org/doc/admin24/overlays.html, I add the codes of "overlay
memeberof" in the file of slapd.conf,then I started the slapd service, the
system give me an error "overlay "memberof" not found" .
   second,I googled the internet and found an article on this
webpage:http://www.redmine.org/projects/redmine/wiki/RedmineLDAP,so I create two
LDIF files as follow:
   the first file :
    dn: cn=module,cn=config
    objectClass: olcModuleList
    cn: module
    olcModulePath: /usr/lib/ldap
    olcModuleLoad: memberof
   the second file:
    dn: olcOverlay=memberof,olcDatabase={1}hdb,cn=config
    objectClass: olcMemberOf
    objectClass: olcOverlayConfig
    objectClass: olcConfig
    objectClass: top
    olcOverlay: memberof
    olcMemberOfDangling: ignore
    olcMemberOfRefInt: TRUE
    olcMemberOfGroupOC: groupOfNames
    olcMemberOfMemberAD: member
    olcMemberOfMemberOfAD: memberOf
after I entered the command "ldapadd -x -D 'cn=Manager,dc=example,dc=com' -W
-f 1.ldif",the system give an error:"ldap_add: Insufficient access (50)"

please help me ,thanks.