about case-sensitive (again)

["cron"<cron@citiz.net>]

Can anybody help me? 

Hello everyone , I'm a freshman of ldap, we're working for applications that authorizating the user by LDAP, we have a "uid" of "teacher", but the users can login by name of "Cron" or "CRon" or something. So I must change the LDAP configuration so that the username can be case-sensitive. 
     so I follow some article like http://www.openldap.org/lists/openldap-software/200211/msg00328.html , but when I change my school.schema by that method of changing the "caseIgnoreMatch" to "caseExactIA5Match" or "caseExactIA5SubstringsMatch"

my school.schema
--------------------------------------------------------------
attributetype (1.1.2.1.3
      NAME 'teacher'
      DESC 'REFC1274:teacher of classroom eschool'
      EQUALITY caseIgnoreMatch  #        case insensitive
      SUBSTR caseIgnoreSubstringsMatch #    case insensitive 
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768}) 

changing by follow .......

attributetype (1.1.2.1.3
      NAME 'teacher'
      DESC 'REFC1274:teacher of classroom eschool'
      QUALITY caseExactMatch
      SUBSTR caseExactSubstringsMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.15{32768}) 

or by follow.....

attributetype (1.1.2.1.3
      NAME 'teacher'
      DESC 'REFC1274:teacher of classroom eschool'
      QUALITY caseExactIA5Match
      SUBSTR caseExactIA5SubstringsMatch
      SYNTAX 1.3.6.1.4.1.1466.115.121.1.26{32768})

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then I restart the slapd services, but that doesn't work