login ekranı sorunu

<?include('admin_items/connect.php');

session_start();
ob_start();

$admin_username = htmlentities(mysql_real_escape_string($_POST["admin_username"]));
$admin_password = md5(md5(htmlentities(mysql_real_escape_string($_POST["admin_password"]))));

$sorgula = mysql_query("SELECT * FROM admin_users WHERE admin_username='{$admin_username}' and admin_password='{$admin_password}'") or die (mysql_error());

$uye_varmi = mysql_num_rows($sorgula);
if($uye_varmi > 0)
{
$_SESSION["giris"] = "true";
$_SESSION["admin_username"] = $admin_username;
$_SESSION["admin_password"] = $admin_password;

setcookie("admin_username",$admin_username,time()+60*60*24);
setcookie("admin_password",$admin_password,time()+60*60*24);

echo str_repeat("<br>", 8)."<center><img src=images/yukleniyor.gif border=0 /> Giriş başarılı, lütfen bekleyiniz..</center>";
header("Refresh: 2; url=main.php");
}

else
{
		
echo str_repeat("<br>", 8)."<center><img src=images/hata.gif border=0 /> Kullanıcı adı veya parola hatalı!</center>";
header("Refresh: 2; url=index.php");
	
}
mysql_close();
ob_end_flush();
?>