Ldap sasl bind(gssapi problem)

Hallo there everyone,
after finishing my server side configuration so as to have the
maximum security
i tried this morning to do a sasl bind with my ldap server ,
my file looks like that:

$ldapbind=ldap_sasl_bind($ldapconn,NULL,NULL,"GSSAPI","TEIPIR.GR","ldapmaster","dn:cn=ldapmaster@TEIPIR.GR,ou=kerberos,dc=teipir,dc=gr");
// verify binding

if ($ldapbind) {
echo "LDAP bind successful..." . "<br />";

every other mech i use seems to work fine but only the gssapi is not
workign from what i can see on the log
i have tried most of the additional commands i found on the net like:

putenv("KRB5CCNAME={$_SERVER['KRB5CCNAME']}");



but still nothing
any idea to make the bind over gssapi so as to have the kerveros ticket exchange actually working

Thank you

----------------------------------------------------------
//export only path file name (remove "file:")
$krb5cache = substr($_SERVER['KRB5CCNAME'],5,strlen($_SERVER['KRB5CCNAME']));
//export it again
putenv("KRB5CCNAME=$krb5cache");
//exoprt it also for apache2
apache_setenv("KRB5CCNAME",$krb5cache);
----------------------------------------------------------




with this lines it works fine.