qualcuno sa dirmi perchè non funzia questo form ?

codice:
<form method="post" action="form.php">                              <fieldset>                                                          <div class="clearfix">                                     <div class="input">                                         <input type="text" value="" id="subject" name="subject" class="input-xxlarge" required placeholder="Oggetto">                                                                                           <div class="clearfix">                                     <div class="input">                                         <input type="text" value="" id="name" name="name" class="input-xxlarge" required placeholder="Nome">                                          <div class="clearfix">                                     <div class="input">                                         <input type="text" value="" id="surname" name="surname" class="input-xxlarge" required placeholder="Cognome">                                                                              </div>                                 </div>                                 <div class="clearfix">                                     <div class="input">                                         <input type="text" value="" id="email" name="email" class="input-xxlarge" required placeholder="Email">                                     </div>                                 </div>                                 <div class="clearfix">                                      <div class="input">                                         <textarea rows="7" name="message" id="message" class="input-xxlarge" required placeholder="Message"></textarea>                                     </div>                                 </div>                                 <div>                                 	<button class="btn btn-wonka-land-3 btn-large" formtarget="_new"><i class='icon-envelope'>[/i] Invia Email</button>                                 </div>                             </fieldset>                         </form>
form.php

Codice PHP:
<?php $to 'miaemail@miaemail.it';   $subject $_POST['subject'];  $email $_POST['email'];  $message $_POST['message'];   $name $_POST['name'];  $surname $_POST['surname'];   if(mail($to$subject$email$message$name$surname )) echo 'Email inviata correttamente'; else echo 'Errore durante invio email!' ?>