title: Add a custom attribute to person class in opendj
body: <p>I follow <a href="http://opendj.forgerock.org/opendj-server/doc/admin-guide/index/chap-schema.html" rel="nofollow">http://opendj.forgerock.org/opendj-server/doc/admin-guide/index/chap-schema.html</a>
  to add a custom attribute to perosn class in opendj</p>
  
  <p>1)create packt-services-user-blog  attribute
  2)create packt-services-user-class class, and add packt-services-user-blog attribute
  3)create custom-attr.ldif
  dn: uid=user.0, ou=People,dc=example, dc=com
  changetype: modify
  add: objectClass
  objectClass: person</p>
  
  <p>add: packt-services-user-blog
  packt-services-user-blog: Testing 1,2,3 ....
  4)
  ./ldapmodify \
  --port 389 \
  --hostname www.openam.example.com \
  --bindDN "cn=Directory Manager" \
  --bindPassword opendj \
  --filename custom-attr.ldif</p>
  
  <p>But I get an error as follows:
  Result:20
  Message: can not modify entity uid=user.0,ou=People,dc=example,dc=com，Cause there are more than one reduplicated value in attribute objectClass : person</p>
  
  <p>I guess this error results from I don't add attribute packt-services-user-blog to person successfully</p>
  
  <p>So How can I fix this problem?</p>