回调Blockchain API无法正常工作？

Question

我正在尝试在收到btc时运行回调，但显示错误，请帮助。

<?php
$secret = 'secret12345';
$my_xpub = 'xpub6CtBowk1kyogwVsfyi92C8HkcyemJ4jYaaXEbXbF15KeTyyihkjhkpUpgmN2TtmDiyPoF 
6T4epFg1pEYpeF76jn7FY3kK5NEF5JUvyWJrb';

$my_api_key = '48d3798792-047e-4870-96c6-d15a798890a9404';
$my_callback_url = 'https://mystore.com? 
 invoice_id=058921123&secret=' . $secret;

$root_url = 'https://api.blockchain.info/v2/receive';
$parameters = 'xpub=' . $my_xpub . '&callback=' . urlencode($my_callback_url) . '&key=' . $my_api_key;

$response = file_get_contents($root_url . '?' . $parameters);
$object = json_decode($response);
echo 'Send Payment To : ' . $object->address;
?>