XML-RPC2 Client (Problem Using Code)

Hello everyone, happy new year! I am trying to use the client logic of XML-RPC2, but find myself unable to instantiate a client object. Here is the test code used: <?

        require_once 'XML/RPC2/Client.php'; // this was changed from XML_RPC2 because of an error trying to find the file
        $client = XML_RPC2_Client('http://localhost/~Kaylum/test//html/rpc/', 'LS_Server.');
        $result = $client->hello('Sergio');
        print($result);

?> The error received in my browser is: Fatal error: Call to undefined function xml_rpc2_client() in /Users/Kaylum/Sites/test/html/test.php on line 3 Can someone assist me with solving this problem? Thank you