sendmany json failed

<?php

function sendMany()
    {
        $url = "http://127.0.0.1:48332";
        $addr = "ztYmK4E...."

        $param = array(
            "address" => "ztSc...",
            "amount" => 0.05
            );
        $json_encoded_param = json_encode($param);

        $data = array(
                     "jsonrpc" => "1.0",
                     "method" => "z_sendmany",
                     "params" => array($addr,array($json_encoded_param)),
                     "id" => "curltest"
                     );
        $json_encoded_data = json_encode($data);

        $handle = curl_init($url);
        curl_setopt($handle, CURLOPT_CUSTOMREQUEST, "POST");
        curl_setopt($handle, CURLOPT_POSTFIELDS, $json_encoded_data);
        curl_setopt($handle, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($handle, CURLOPT_HTTPHEADER, array(
                                                'Content-Type: application/json',
                                                'Content-Length: ' . strlen($json_encoded_data))
        );

        $result = json_decode(curl_exec($handle));
        curl_close($handle);

        return $result;
    }

sendMany();

?>