Variable type is null in remote class

Here is my main class

class pMr {
    const VERSION = '0.0.3';
    public $_connection;
    private $_sessionName = 'LoginSession';

    public function __construct($function = null) {
        ...
            $this->buildConnection('Predis');
        ...
    }

    private function buildConnection($type = 'Predis') {
        ...
            if($type == 'Redis') {
                ...
            } else if($type == 'Predis') {
                try {
                    $this->_connection = new Predis\Client(array(
                        'host'     => $_SESSION[$this->_sessionName]['hostname'],
                        'password' => $_SESSION[$this->_sessionName]['password'], 
                        'database' => $_SESSION[$this->_sessionName]['database'], 
                    ));
                } catch (ClientException $e) {
                    die($e->getMessage());
                }
                var_dump(gettype($this->_connection));  
            }
        }
    }
}

Now, when that code runs, I get string(6) "object", which is expected. Now, here is another class, which is loaded inside the main class and then executed (a function is called).

class Interface {
    static $_execOnLoad = true;
    public static function getRedisVersion() {
        global $pMr;
        var_dump(gettype($pMr->_connection));
    }
}

Now, in that function (when its called), returns NULL. This is the same variable that returns as an object in the above code. Why is this, and what is the work ar开发者_开发问答ound?

Perform var_dump($pMr); for both objects and see its object#. I bet you just have different objects.