PHP LDAP search parent group

Hi, I need to get the LDAP groups a user is member of (memberof). The problem is that there are multiple levels of groups, and I need to get all levels. example userA is member of group A B and C group A is member of (included in) group D If I make a simple query on the LDAP server to fetch the memberof of userA, it returns A, B and C. I need to get also D because group A is in group D In PHP I use the statement : $list = ldap_search($conn, "$userdn,$basedn", "samaccountname=$name", array('memberof')); //samaccountname is the Windows login name I make a ldap_search() but I also tried with ldap_list() and ldap_read() without change I used the options ldap_set_option($conn, LDAP_OPT_REFERRALS, 0); ldap_set_option($conn, LDAP_OPT_PROTOCOL_VERSION, 3); //active Directory on 2003 server Is there a parameter I could add to PHP so as to get the parent groups? What is the LDAP_OPT_REFERRALS option ??? Thank you, Vincent