agan-agan Master Web Sya Mau tanya tentang source code ini

<?php
session_start();
include "./includes/koneksi.php";


//Tangkap variabel
$user = $_POST['txtuser'];
$pass = $_POST['txtpass'];
//Cocokkan ke database tabel admin
$a = "SELECT * FROM owner WHERE owner_user = '$user' AND owner_pass = MD5('$pass')";
$b = mysql_query($a);
$jum = mysql_num_rows($b);
//Cek jumlah data hasil query
if($jum==0){
//Kalo user dan password salah
echo "[removed]alert('User, Pass Salah');[removed]";
echo "<meta http-equiv='refresh' content='2;url=index.php' />";
}else{
//kalo user dan password benar
$c = mysql_fetch_array($b);
$_SESSION['user'] = $c['owner_user'];
$_SESSION['nama'] = $c['owner_nama'];
echo "[removed]alert('Login berhasil');[removed]";

}


?>

apa ada yang salah karena tiap masukin user dan passwordnya selalu salah