Ошибка function query() on a non-object

db.php

<?php
class Dbh {
private $servername;
private $username;
private $password;
private $dbname;
private $charset;
public function connect() {
$this->servername = 'localhost';
$this->username = 'root';
$this->password = 'exh05t9a';
$this->dbname = 'hash';
$this->charset = 'utf8';
try {
    $dsn = "mysql:host=".$this->servername.";dbname=".$this->dbname.";charset=".$this->charset;
    $pdo = new PDO($dsn, $this->username, $this->password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    return $dpo;
} catch (PDOExeption $e) {
    echo "Connection failed: ".$e->getMessage();
}
}
}
?>

password.php

<?php
class Password extends Dbh {
public function getUserPassword() {
    $stmt = $this->connect()->query("SELECT password FROM users");
    while ( $row = $stmt->fetch() ) {
        $password = $row['password'];
        return $password;
    }
}
}

Хочу сделать, чтобы с БД выводил пароль, пишет: Call to a member function query() on a non-object in W:\domains\hash\password.php on line 5

Строка 5: $stmt = $this->connect()->query("SELECT password FROM users");