Scalar value

Dobrý deň, prosím Vás, vie mi niekto vysvetlit toto varovanie ?

Warning: Cannot use a scalar value as an array in .../login.php on line 17

Nikdy predtym mi to nerobilo, nemenila sa konfiguracia servra, uz som skusal vyhadzat vsetky mozne kody ale stale to pretvrava. Vedeli by ste mi pomoct ako sa tomu da predist ? Vdaka

<?
if($faza == 2) {
$db->free_result("user_login");
$heslo_md5 = md5($heslo);
$db->add_result("user_login", "SELECT * FROM users WHERE login='$login' AND heslo='$heslo_md5' AND aktivne='y' AND zmrazene='n'");

$db->fetch("user_login");

if($db->num_rows("user_login") == 1) {

$registruj = @session_register("user");
if($registruj) {
$sec_kod = md5($db->get("user_login", "heslo").$db->get("user_login", "login").'kod'.date(U));
$_SESSION["user"]["kod"] = $sec_kod; //sec_kod do session
$db->query("UPDATE users SET kod='$sec_kod' WHERE login='$login'");
$us_idd = $db->get("user_login","id");
$db->query("INSERT INTO memoir (id, uzivatel, datum, sprava, nove) VALUES ('','$us_idd',now(),'<strong>Úspešné prihlásenie</strong> z IP adresy <strong>$REMOTE_ADDR</strong>.','n')");
header("Location: main.php");

}

} else {
$db->add_result("vyber_usera", "SELECT id FROM users WHERE login='$login' AND aktivne='y' AND zmrazene='n'");

...