OlcLimits : sizelimit exceeded (openldap 2.5.16)

Dears,

I've an issue with one user for which I set its limits to "unlimited" but which get err=4 (sizelimit exceeded).

This is in the context of a META ldap fronted to a ldap backend.

If I do the ldapsearch of this user in CLI directly on the ldap backend where the OlcLimits are set for it, this works perfectly, no err=4 errors but if this ldapsearch comes from the META ldap frontend with the same user which is used in the olcDbIDAssertBind as Binddn, it's failling with err=4 !!??

I did check ldap logs at back end and they are identical in both cases except the err=4.

I don't see what can be the cause ??

Any help will be appreciate !!

Thx in advance, Jean-Luc.