Problemas con Actualizacion

[ambichol]

Hola nuevamente, tengo un problema con una actualizacion de registros, realizo la insercion de los registros pero al momento de dar click en el boton actualizar no los hace, sin embargo si imprime la variable(puse una etiqueta para ver si las variables no se pierden).

agradeceria me pudiesen apoyar en este caso.....

Código PHP:

<?PHP
 
$db = new ezSQL_mysqli(db_user,db_password,db_name,db_host);
//<UPDATE>
if (isset($_POST['update'])){
    if ( $_POST['nacl'] == md5(AUTH_KEY.$db->get_var("select last_login from site_users where user_id = $user_id;")) ) {
    //authenticaion verified, continue.
    $dni = $db->escape($_POST['dni']);
    $call_request = $db->escape($_POST['call_request']);
    $nw_user_name = $db->escape($_POST['nw_user_name']);
    $db->query("UPDATE site_aplications SET usuario='$nw_user_name' WHERE (dni = '$dni') and (aplicativo = '$call_request');");
    $actionstatus = "<div class=\"alert alert-success\" style=\"max-width: 250px;\">
    <button type=\"button\" class=\"close\" data-dismiss=\"alert\">&times;</button>
    Modificacion exitosa.
    </div>";
    //$db->debug();
    }
}
?>
 
<form action="fhd_edit_user_aplication.php" method="post" class="form-horizontal">
<table class="<?php echo $table_style_2;?>">
    
    <tr><td>Usario</td>
    <td><input type="text" name="dni" value=""</td></td></tr>
    
    <tr><td>Aplicativo</td><td><select name='call_request' >
    <?php $request_name = $db->get_results("select type_id,type_name from site_types where type=2 order by type_name");
    foreach ($request_name as $request )
    {?>
    <option value='
    <?php echo $request->type_name;?>'<?php if($request->type_name == $call_request){echo ' selected';}?>><?php echo $request->type_name;?></option>
    <?php } ?>
    </select></td></tr>
    
    <tr><td>Nuevo usuario</td>
    <td><input type="text" name="nw_user_name" value=""></td></tr>
 
    <? $url_user_id=$nw_user_name?>
    <tr><td>ID </td>
    <td><?php echo $url_user_id;?></td></tr>
    
    
</table>
<input type='hidden' name='url_user_id' value='<?php echo $url_user_id;?>'>
<input type='hidden' name='nacl' value='<?php echo $nacl;?>'>
<input type='hidden' name='update' value='1'>
<input type="submit" value="actualizar" class="btn btn-primary btn-large">
</form>
 
<?php
if(isset($_SESSION['name'])){
//the session variable is registered, the user is allowed to see anything that follows
echo "<p><strong>Name:</strong> " . $_SESSION['name'] . "</p>";
}
include("includes/footer.php");
?>
 

saludos...