Php class with statc function to connect to database - pdo

Question

I have this class to connect to my database, but when I try to use it, always return null.
if I use these credentials in a single php file without class and static function, it works.
This is how I use it
<?php
include 'bdconexion.php';
$var ="hola";
$pdo=BaseDatos::Conectar();
print '<h3>PDO: simple select</h3>';
foreach($pdo->query( 'SELECT * FROM productos;' ) as $row)
{
echo $row['descripcion'];
}
Some help will be great
class BaseDatos
{
private static $bdname = 'bd';
private static $bdhost = 'localhost';
private static $user = 'root';
private static $pass = 'pass';
//private static $mssqldriver = '{SQL Server}';
//private static $mssqldriver = '{SQL Server Native Client 11.0}';
//private static $mssqldriver = '{ODBC Driver 11 for SQL Server}';
private static $conn = null;
public function __construct()
{
die('La funcion de inicio no es permitida');
}
public static function conectar()
{
if (null==self::$conn) {
try {
$conn = new PDO("mysql:host=".self::$bdhost.";dbname=".self::$bdname,self::$user,self::$pass);
} catch (PDOException $e) {
die($e->getMessage());
}
}
return self::$conn;
}
public static function desconectar()
{
self::$conn=null;
}
}