Problem with email->attach() on CI 3.1.2

Hi.
I'm have a problem.

final public function send_order_to_email($id_order, $email, &$body, $file_attach = null)
    {
        $this->load->library('email');
        $this->email->initialize(array(
            'useragent' => 'useragent',
            'mailtype' => 'html',
            'validate' => true
        ));
        $this->email->from('[email protected]', 'useragent');
        $this->email->to($email);
        $this->email->subject('Order №' . $id_order);
        $this->email->message($body);
        if (!is_null($file_attach)) {
            $this->email->attach($file_attach, 'attachment', 'invoice_' . $id_order . '.pdf');
        }
        return (bool)$this->email->send();
    }
WHERE:
$file_attach= base_url( ' /email/attch/myfile.pdf ' ); (file is present on server)
$email = [email protected]

Problem: on local server - code works fine. On hoster's server - letters to the email come, but file size is 0 bytes