google api freebase problem

Does anyone know why this google php API does not work? wanted to use this api to destroy data from a page for example:
Mark Zuckerberg
Programmer
Born: May 14, 1984 (31 years), White Plains, New York, USA
Spouse: Priscilla Chan (since 2012)
Shareholders' equity: USD 35.7 billion (2015)
Daughter: Maxima Zuckerberg
Sisters: Randi Zuckerberg, Arielle Zuckerberg, Donna Zuckerberg
Membership: Karen Zuckerberg, Edward Zuckerberg

$freebase_api_key);
  $url = $service_url . $topic_id . '?' . http_build_query($params);
  $ch = curl_init();
  curl_setopt($ch, CURLOPT_URL, $url);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
  $topic = json_decode(curl_exec($ch), true);
  curl_close($ch);
  echo $topic['property']['/type/object/name']['values'][0]['value'];
?>