modification of objectclass of active Directory

[TOUNSI]

hi at every body i'am trying to modify the attribut : object class in Active Directory
with PHP

this my code

$entry["objectclass"][0] = "organisation";

$entry["objectclass"][1]="university";
$entry["objectclass"][2]="lmd";


$a=ldap_mod_replace ($ds,$dn,$entry);

but i've this message
modify no such attributs..
i want to know what is my error
thank for you helping

[pbmods]

Heya, Tounsi.

You're trying to replace an attribute that does not already exist. Try using ldap_mod_add() instead.