From Facebook Developer Wiki

I encountered a problem that:

$facebook->api_client->call_method('facebook.data.setUserPreferences',array(0 => array('pref_id' => 3,'value' => 'dongfu song'),1 => array('pref_id' => 4,'value' => 'xiaoliang song')));

The result I got is that Fatal error: Uncaught exception 'FacebookRestClientException' with message 'Incorrect signature' in /usr/local/imad/web/htdocs/cutestudy/facebookapi_php5_restlib.php:1315 Stack trace: #0 /usr/local/imad/web/htdocs/cutestudy/index.php(111): FacebookRestClient->call_method('facebook.data.s...', Array) #1 {main} thrown in /usr/local/imad/web/htdocs/cutestudy/facebookapi_php5_restlib.php on line 1314. But when I called

$facebook->api_client->call_method('facebook.data.setUserPreference',array('pref_id' => 4,'value' => 'xiaoliang song'));

The result is right. Why? Please help me to solve it, thanks. [I debugged them and I found such two calls had the same signature-7e0c9647722714e2e56d9e29-588817767]