PHP cURL取消订阅PayPal问题

<?php
// 创建cURL会话
$ch = curl_init();

// 设置cURL选项
curl_setopt($ch, CURLOPT_URL, 'https://api.paypal.com/v1/billing/subscriptions/{subscription_id}/cancel');
curl_setopt($ch, CURLOPT_CUSTOMREQUEST, 'POST');
curl_setopt($ch, CURLOPT_HTTPHEADER, array(
    'Content-Type: application/json',
    'Authorization: Bearer {access_token}'
));
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);

// 执行cURL请求
$response = curl_exec($ch);

// 处理响应
if ($response === false) {
    echo 'cURL Error: ' . curl_error($ch);
} else {
    $httpCode = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    if ($httpCode == 200) {
        echo '取消订阅成功';
    } else {
        echo '取消订阅失败';
    }
}

// 关闭cURL会话
curl_close($ch);
?>