在非对象PHP PDO上调用成员函数prepare()

can you help me? I'm getting a little problems with my script.

database.php

class Database {

    protected $host = "localhost";
    protected $dbname = "phppdo";
    protected $user = "root";
    protected $pass = "";
    protected $DBH;

    public function __construct() {
        try {
            $this->DBH = new PDO("mysql:host=$this->host;dbname=$this->dbname", $this->user, $this->pass);
        }
        catch (PDOException $e) {
            die($e->getMessage());
        }
        return $this->DBH;
    }
}

user.php

date_default_timezone_set('America/Sao_Paulo');
include 'database.php';
class User extends Database {

    private $name;
    private $email;
    private $date;

    function __construct($name, $email) {
        $this->$name = $name;
        $this->$email = $email;
    }

    public function insert() {
        $STH = $this->DBH->prepare("INSERT INTO `phppdo` VALUES(NULL, :username, :email, UNIX_TIMESTAMP())");
        $STH->execute(array(
            ':name' => $name,
            ':emal' => $email,
        ));
    }
}

if(isset($_POST['submit'])) {
    $x = new User($_POST['name'], $_POST['email']);
    $x->insert();
}

The script isn't working! I'm getting Call to a member function prepare() on a non-object on line 16 = $STH = $this->DBH->prepare("INSERT INTOphppdoVALUES(NULL, :username, :email, UNIX_TIMESTAMP())");

I don't know why it's happening... Can you help me? Thank you!!

Make your User class like below :

class User extends Database {

private $name;
private $email;
private $date;

function __construct($name, $email) {

    $this->name = $name;
    $this->email = $email;
    parent::__construct();
}

public function insert() {

    $STH = $this->DBH->prepare("INSERT INTO `phppdo` VALUES(NULL, :name, :email, UNIX_TIMESTAMP())");
    $STH->execute(array(
        ':name' => $this->name,
        ':email' => $this->email,
    ));
}
}