Open LDAP ACL and Group

Hello,
I have a problem with acl and group.
I configured a proxy slapd and add acl (see slapd.conf below)

When I run a ldapsearch command with user 'Test User' the attributes are displayed. It's Ok

But when I run the same ldapsearch command with user 'Synchro1 User' the message 'Insufficient access (50)' are displayed. It's not ok
The user 'Synchro1 User' is member of CN=Grp_Users_UG,OU=Gina,OU=Applications,DC=activedir,DC=example,DC=ch

Are you an idea ?
Thank you for you help
Dysan

My environment
---------------------
ldapproxy server is CentOS release 5.9 (Final) openldap version 2.3.43
dc1-test Windows Server 2008 R2 (Domain Controler)

Ldapsearch command
-------------------
$ ldapsearch -x -LLL -H ldaps://ldapproxy.example.ch:636 -D "CN=Test User,OU=TST,OU=USERS,DC=activedir,DC=example,DC=ch" -W -b "dc=activedir,dc=example,dc=ch" -s sub cn=*
Enter LDAP Password:
dn: ........
...

$ ldapsearch -x -LLL -H ldaps://ldapproxy.example.ch:636 -D "CN=Synchro1 User,OU=TST,OU=USERS,DC=activedir,DC=example,DC=ch" -W -b "dc=activedir,dc=example,dc=ch" -s sub cn=*
Enter LDAP Password:
Insufficient access (50)

slapd.conf
----------
include         /etc/openldap/schema/core.schema
include         /etc/openldap/schema/cosine.schema
include         /etc/openldap/schema/inetorgperson.schema
include         /etc/openldap/schema/nis.schema
allow bind_v2

pidfile         /var/run/openldap/slapd.pid
argsfile        /var/run/openldap/slapd.args
TLSCipherSuite HIGH:-SSLv2
TLSCACertificateFile /etc/openldap/cacerts/cacerts.crt
TLSCertificateFile /etc/openldap/cacerts/ldapproxy.example.ch.crt
TLSCertificateKeyFile /etc/openldap/cacerts/ldapproxy.example.ch.key

loglevel -1
disallow        bind_anon

# AD
database        ldap
suffix          "dc=activedir,dc=example,dc=ch"
uri             "ldaps://dc1-test.example.ch/"
readonly on
rebind-as-user
lastmod off

access to attrs=displayname,sn,givenname,mail,telephoneNumber
by dn.exact="CN=Test User,OU=TST,OU=USERS,DC=activedir,DC=example,DC=ch" read
by group.exact="CN=Grp_Users_UG,OU=Gina,OU=Applications,DC=activedir,DC=example,DC=ch" read
by * none

# The users must see the entry itself
access to attrs=entry
by dn.exact="CN=Test User,OU=TST,OU=USERS,DC=activedir,DC=example,DC=ch" read
by group.exact="CN=Grp_Users_UG,OU=Gina,OU=Applications,DC=activedir,DC=example,DC=ch" read
by * none

# Other attributes, others users have no access
access to *
by * none
#---------------------------------------------------------------------------------------------------------------
slapd.conf end