Call to a member function getLoginUrl() on a non-object

[eluser]ibnclaudius[/eluser]
In my __construct i have this:

Code:

if ($this->facebook['active'] === TRUE)
  {
   $this->CI->load->library('facebook', $this->facebook['config']);
  
   $id = $this->CI->facebook->getUser();
  
   if ($id)
   {
    try {
     $user = $this->CI->facebook->api('/me');
    }
    catch (FacebookApiException $e)
    {
     error_log($e);
     $id = NULL;
    }
   }
   else
   {
    echo $this->CI->facebook->getLoginUrl();
   }
  }

In this case, $this->CI->facebook->getLoginUrl() return what I want, but trying to retrieve the login url using a method give this error "Call to a member function getLoginUrl() on a non-object"

Code:

public function facebook_login_url()
{
  return $this->CI->facebook->getLoginUrl();
}

Why?