Is there a special trick to reading the 'ndsHomeDirectory' LDAP attribute?

I am not having trouble reading any other attributes, but the variable I am using to enumerate this attribute is not even set after a ldap_search() and a ldap_get_entries().

Netware 6.5, latest and greatest, and I have verified that 'ndsHomeDirectory' is included in the LDAP_GROUP mappings.

$conn = valid ldap_connect
$username = valid username
$bind = valid ldap_bind
$dnvalue = valid dn

$filter = "(&objectClass=user)(cn=".$username)";
$justthese = array("dn", "surname", "mail", "ndsHomeDirectory");
$result = ldap_search($conn, $dnvalue, $filter, $justthese);
$values = ldap_get_entries($conn, $result);

any reference to $values['ndsHomeDirectory'] generates "undefined index" error. Other references (surname, mail) work fine.