Hello i have an html form and i'm posting data but i'm unable to get the posted data on a php page (same page) can you please help me. thanks in advance

<div class="left">
<form name="form_signin" method="post" onsubmit="return signinValid();" >
    <table>
        <tr>
            <td>
                Email :
            </td>
            <td>
                <input type="text" id="email" length ="40">
            </td> 
        </tr>
        <tr>
            <td>
                Mot de Passe :
            </td>
            <td>
                <input type="password" id ="pass" length ="40">
            </td>
        </tr>
        <tr>
            <td>
                &nbsp;
            </td>
            <td>
                <input type="submit" value="Connexion" length ="40">
            </td>
        </tr>

    </table>


</form>

<?php
include 'includes.php';
include DB_CONNECT_FILE;
//session_start();
print_r($_POST); // prints an empty array even if fields are filled

$smart->assign('tpl_file',TEMPLATES_DIR.'signin.html');
$smart->display(TEMPLATES_DIR."with_right.html");

include DB_DISCONNECT_FILE;

?>