Login Nepřihlašuje

<?php
session_start(); 

     
        if(isset($_SESSION['prihlasen']) and $_SESSION['prihlasen']==1){
          echo "
<strong>Uživatelsk&eacute; jm&eacute;no</strong>: ".$_SESSION['login'] ." | <a href='ur.php'>Uprava</a> | <a href='logout.php?logout=yes'>Odhl&aacute;sit se </a>

";
        }else{
          echo '<form action="log2db.php" method="post">
  <p>
    <input type="hidden" name="sent" value=""/>
  </p>
  <table cellspacing="0" cellpadding="0">
    <tr>
      <td><label for="login">Login</label></td>
      <td><label for="pass">Heslo</label></td>
    </tr>
    <tr>
      <td><input type="text" name="jmeno" maxlength="32"></td>
      <td><input type="password" name="heslo" maxlength="32"></td>
      <td>
        <input type="submit" name="send" value="Přihl&aacute;sit se"/>
      </td>
    </tr>
  </table>
  <p>&nbsp;</p>
  </form>';
        }

 
            if (IsSet($_GET['page'])){        
              $soubor=$_GET['page'];
              $soubor2= dirname($_SERVER['SCRIPT_FILENAME'])."/".$soubor.".php";
              if(file_exists($soubor2)){   
                include $soubor2;
              }else{             
                include "inc/error404.php";
              }
            }
      
          if(isset($_GET['Alert'])){
            require "inc/error_msg.php"; 
            $JsAlert=$_GET['Alert'];
            echo '<script language="javascript" type="text/javascript">alert("'.$Rvi[$JsAlert].'");</script>';
          }
          ?>

<?php
ob_start();

session_start();
if(isset($_POST['jmeno'])){
  require_once 'db.php';
  $name = $_POST['jmeno'];
  $pass = md5($_POST['heslo']);
    $query = mysql_query("SELECT * FROM `uzivatele` WHERE `jmeno` = '$name' and `heslo` = '$pass'") or die (mysql_error());

      $Vysledek = mysql_fetch_array($query);
        if($Vysledek['jmeno']){ // pokud tato promenná obsahuje data, bylo zadané správné jméno a heslo
          
          $_SESSION['prihlasen'] = 1;
          $_SESSION['login'] = $Vysledek['jmeno'];
          $_SESSION['UserId'] = $Vysledek['id'];
          $_SESSION['UserSex'] = $Vysledek['pohlavi'];
          $_SESSION['UserMail'] = $Vysledek['mail'];
          $bl="index.php";
          header("location: $bl"); 
          exit;
        }else{
          $bl="register.php";
          header("location: $bl");
          exit;
        }
    mysql_free_result($query);
}else{
  echo "Zde nic není.";
}
ob_end_flush();
?>