paypal当前类范围没有父级时，无法访问parent ::

Question

致命错误：当前类范围没有父级时访问parent ::

使用sdk-core-php进行paypal时。

我的代码是：

    $apiContext = new ApiContext(new OAuthTokenCredential(client_id, secret));
    $apiContext->setConfig(array(
        'mode' => 'Live',
        'http.ConnectionTimeOut' => 30,
        'log.LogEnabled' => false,
        'log.FileName' => 'PayPal.log',
        'log.LogLevel' => 'FINE'
    ));
    try {
        $payment = Payment::get($payment_id, $apiContext);
    } catch (PayPal\Exception\PPConnectionException $ex) {
        echo $ex->getMessage();
        exit();
    }