strange behavior of openldap: missing record in ldapsearch

[Zhang Weiwu <zhangweiwu@realss.com>]

First there is a record with value that fits (businessCategory=C16.1*), 
verified in STEP 1, second, searching with '(businessCategory=C16.1*)' 
couldn't find it, demonstrated in STEP2.

===== STEP 1 =====

$ ldapsearch -xD uid=supertuxadmin,ou=contacts,ou=china,dc=ahk,dc=de -W -b ou=contacts,ou=china,dc=ahk,dc=de '(o=Homag Machinery * Co., Ltd.)' dn businessCategory
# extended LDIF
#
# LDAPv3
# base <ou=contacts,ou=china,dc=ahk,dc=de> with scope subtree
# filter: (o=Homag Machinery * Co., Ltd.)
# requesting: dn businessCategory 
#

# SH0180, contacts, china, ahk.de
dn: uid=SH0180,ou=contacts,ou=china,dc=ahk,dc=de
businessCategory: C16.10 Sawmilling and planing of wood
businessCategory;lang-zh:: QzE2LjEwIOmUr+acqOWPiuWIqOacqA==
businessCategory;lang-de:: QzE2LjEwIFPDpGdlLSwgSG9iZWwtIHVuZCBIb2x6aW1wcsOkZ25
pZXJ3ZXJrZQ==

# search result
search: 2
result: 0 Success

# numResponses: 2
# numEntries: 1

===== STEP 2 =====

$ ldapsearch -xD uid=supertuxadmin,ou=contacts,ou=china,dc=ahk,dc=de -W -b ou=contacts,ou=china,dc=ahk,dc=de '(businesscategory=C16.1*)' dn

# extended LDIF
#
# LDAPv3
# base <ou=contacts,ou=china,dc=ahk,dc=de> with scope subtree
# filter: (businesscategory=C16.1*)
# requesting: dn 
#

# German_Perfect_2, contacts, china, ahk.de
dn: uid=German_Perfect_2,ou=contacts,ou=china,dc=ahk,dc=de

# Keenmax, contacts, china, ahk.de
dn: uid=Keenmax,ou=contacts,ou=china,dc=ahk,dc=de

# SH1625, contacts, china, ahk.de
dn: uid=SH1625,ou=contacts,ou=china,dc=ahk,dc=de

# id6505, contacts, china, ahk.de
dn: uid=id6505,ou=contacts,ou=china,dc=ahk,dc=de

# Davidyang1981, contacts, china, ahk.de
dn: uid=Davidyang1981,ou=contacts,ou=china,dc=ahk,dc=de

# search result
search: 2
result: 0 Success

# numResponses: 6
# numEntries: 5

======== FINISH ======


I expected to see uid=SH0180,ou=contacts,ou=china,dc=ahk,dc=de in the 
search result in step 2 but couldn't. Similiar problem happen on 
commonName as well, on both of our two installations, one is running 
2.4.9 and the other 2.3.30. Both using hdb.

It is totally confusing to me that I don't even know where to start look 
for the problem. Should I also attach full slapd.conf?

Thanks for any input in advance. I am totally clueless now, even after 
running the installation for 3 years it's the first time see such 
frastrating situation. Thanks.

Best regards
Zhang Weiwu