modifyTimeStamp not modified on replica

[jehan procaccia <jehan.procaccia@it-sudparis.eu>]

Hello

when I modify the mail attribute on the master, the attribute is 
correctly replicated on the replica, but the modifyTimeStamp isn't !?
shouldn't it be modified !?

The master is runing openldap-servers-2.3.43-12.el5_7.10
the replica that failes to replicate modifyTimeStamp  is an 
openldap-servers-2.4.23-20.el6.i686
on a openldap-servers-2.3.43-12.el5_7.10 replica, modifyTimeStamp is 
correctly updated !
could it be a openldap version incompatibility ?
or perhaps an ACL miss-configuration !?

Thanks for your help .