Php pdo POST add data to database with function PDO

I am trying to insert some datas in DB with the following function (I don't get any errors but datas don't get added in my DB)

File name=insertuserdb:

<?php
  function insertUser($U,$P,$E)
   {
    $conn = connPDO();//*function to connect to my DB on the other file
    $query = ("INSERT INTO user (Username, Password, Email) VALUES     (:User,:Pass,:Email)");
    $conn_prepare = $conn->prepare($query);
    $conn_prepare->execute(array( "User" => $U,"Pass" => $P,"Email" =>$E ));
    $id = $conn->lastInsertId();
    $conn_prepare->closeCursor();
    return $id;
 }
?>

AND (my connection function (works/sorry for french)) file name=dbc3.php:

   <?php

     function connPDO()
     {
$PARAM_hote='localhost'; // le chemin vers le serveur
$PARAM_port='';
$PARAM_nom_bd='mygcpage'; // le nom de votre base de données
$PARAM_utilisateur='root'; // nom d'utilisateur pour se connecter
$PARAM_mot_passe=''; // mot de passe de l'utilisateur pour se connecter
try {
    $connexion = new    PDO('mysql:host='.$PARAM_hote.';port='.$PARAM_port.';dbname='.$PARAM_nom_bd, $PARAM_utilisateur, $PARAM_mot_passe);
    return $connexion;
}
catch(Exception $e) {
    echo 'Erreur : '.$e->getMessage().'<br />';
    echo 'N° : '.$e->getCode();
    die;
}

} $conn = connPDO(); if ($conn) { echo "connected"; } else { echo "ERROR: Could not connect!"; } ?>

finally (my form) file name=login.php:

<form method="POST" action="login.php">
                    <table id="reg">
                    <th>Please the fill in the following:</th>
                        <tr><!--Username -->
                            <td>
                                <p>Username:</p>
                            </td>
                            <td>
                                <input type="text" name="username" />
                            </td>
                        </tr>
                        <tr>
                            <td>
                                <p>Password:</p>
                            </td>
                            <td>
                                <input type="password" name="pass1" />
                            </td>
                        </tr>
                        <tr>
                            <td>
                                <p>Comfirm Password:</p>
                            </td>
                            <td>
                                <input type="password" name="pass2" />
                            </td>
                        </tr>
                        <tr>
                            <td>
                                <p>Email:</p>
                            </td>
                            <td>
                                <input type="text" name="email" />
                            </td>
                        </tr>
                        <tr>
                            <td>
                                <input type="submit" name="register" />
                            </td>
                            <td></td>
                        </tr>
                    </table>
                </form>