Problema SESSIONI e COOKIE

[lazytime]

Io non capisco, non riesco a far funzionare le sessioni e né i Cookie, qualcuno può aiutarmi?

Ci sono due file login.php:

session_start();
include 'config.php';
if(isset($_POST['log']))
{    
    $chat = 'originale';
    if(isset($_POST['chat'])) $chat = $_POST['chat'];
    
    $nome_u = mysql_real_escape_string($_POST['nick']);
    $password = mysql_real_escape_string(md5($_POST['pass']));
    
    switch($_POST['set'])
    {
        case 'reg':
            $my_avatar = mysql_real_escape_string('http://media-cache-ec0.pinimg.com/236x/43/db/e7/43dbe7b1521057762f0144260cbf5a0d.jpg');
            $my_ip = mysql_real_escape_string($_SERVER['REMOTE_ADDR']);
            $my_power = 0;
            $now_on_the_line = time();
            $res_users = $DB->query("SELECT nome_u FROM users_bd_enchanted WHERE nome_u = '$nome_u'");
            if($res_users->num_rows >= 1)
            {                
                header("Location:main.php?ErrorReg=1");
            }
            else
            {
                $DB->query("INSERT INTO users_bd_enchanted (nome_u,passw_i,avatar_e,ip,date_reg,power,online_n) VALUES('$nome_u','$password','$my_avatar','$my_ip',now(),'0','$now_on_the_line')");
            }
        break;
        
        case 'log':
            if(isset($_POST['cookie'])) $cookiexists = true;
            $res_users = $DB->query("SELECT * FROM users_bd_enchanted WHERE nome_u = '$nome_u' AND passw_i = '$password'");
            if($res_users->num_rows == 0)
            {            
                header("Location:main.php?ErrorLog=1");
                exit();
            }
            else
            {
                $fetch_users = $res_users->fetch_assoc();
                $my_id = $fetch_users['avatar_e'];
                $my_avatar = $fetch_users['avatar_e'];
                $my_ip = $fetch_users['ip'];
                $my_power = $fetch_users['power'];
                $now_on_the_line = time();
            }
        break;
    }
    if(isset($cookiexists))
    {            
        $expire=time()+60*60*24*7;
        setcookie('log',true,$expire);
        setcookie('avatar',$my_avatar,$expire);
        setcookie('nome',$nome_u,$expire);#,'/','lazytime.altervista.org', 1
        setcookie('power',$my_power,$expire);
    }        
    $_SESSION['log'] = true;
    $_SESSION['nome'] = $nome_u;
    $_SESSION['avatar'] = $my_avatar;
    $_SESSION['power'] = $my_power;
    $_SESSION['diz'] = 'normal';
    switch($chat)
    {
        case 'Originale':header("Location:Sneh/");break;
        case 'Rapida':header("Location:Sneh/handy/");break;
    }
}
else
{
    header("Location:main.php");
}
?> 

e il file index.php:

session_start();
#se printo i cookie non si vede nulla se printo  la sessione power o  avatar v'è null