ldapadd error.

[zhp <zhp@ustc.edu>]

This is my test1.ldif:
#Orgnization CEO
dn: cn=ceo,dc=example,dc=com
objectclass: organizationRole
cn: ceo:
description: The CEO of the Organization
 
    And I add it to the datebase with the command:
  [root@localhost ldif]# ldapadd -f test1.ldif -x -D 
'cn=Manager,dc=example,dc=com' -w secret

   And this is the output:
adding new entry "cn=ceo,dc=example,dc=com"
ldap_add: Invalid syntax (21)o
       additional info: objectclass: value #0 invalid per syntax

And when i change the objectclass to anyone other than 
organizationRole, it works well.
   what is the matter?
   Thanks.