Braintree无法执行收费:自定义字段无效:描述

我们使用的是Laravel 5.2和收银员/Braintree。

我们有一个基于订阅的网站，可以找到。这些是每月定期会员套餐。

我们现在正试图在几天的品尝器中添加一次充电。它似乎都工作得很好，直到最后一步，当我们得到一个错误，说描述无效。查看文档和源代码，我们无法找到这不起作用的原因。

代码如下:

$plan = $request->get('plan');
$coupon = $request->get('coupon');
$user = $this->user;
if ( false === $user->hasBraintreeId() ){
    $customer = $user->createAsBraintreeCustomer($request->get('payment_method_nonce'), array());
    $user->setCustomerId($customer->id);
    $user->save();
} else {
    $customer = $user->asBraintreeCustomer();
}
if ( $plan == '5-day-taster' ){ // One off payment
    $this->user->invoiceFor('5-day-taster', 5.99);
} elseif ( $plan == '10-day-taster' ){ // One off payment
    $this->user->invoiceFor('10-day-taster', 9.99);
} elseif ( $plan == 'personal-standard' ){ // Subscription(s)
    if ( isset($coupon) && !empty($coupon) )
        $this->user->newSubscription($plan, $plan)
            ->withCoupon($coupon)
            ->create($request->get('payment_method_nonce'), [
                'email' => $this->user->email,
            ]);
    else
        $this->user->newSubscription($plan, $plan)
            ->create($request->get('payment_method_nonce'), [
                'email' => $this->user->email,
            ]);
} 

得到以下错误:

Exception in Billable.php line 41:
Braintree was unable to perform a charge: Custom field is invalid: description.

来自Braintree的源代码(未编辑，仅供参考):

/**
     * Make a "one off" charge on the customer for the given amount.
     *
     * @param  int  $amount
     * @param  array  $options
     * @return 'Braintree'Transaction
     */
    public function charge($amount, array $options = [])
    {
        $customer = $this->asBraintreeCustomer();
        $response = BraintreeTransaction::sale(array_merge([
            'amount' => $amount * (1 + ($this->taxPercentage() / 100)),
            'paymentMethodToken' => $customer->paymentMethods[0]->token,
            'options' => [
                'submitForSettlement' => true,
            ],
            'recurring' => true,
        ], $options));
        if (! $response->success) {
            throw new Exception('Braintree was unable to perform a charge: '.$response->message);
        }
        return $response;
    }
    /**
     * Invoice the customer for the given amount.
     *
     * @param  string  $description
     * @param  int  $amount
     * @param  array  $options
     * @return 'Braintree'Transaction
     */
    public function invoiceFor($description, $amount, array $options = [])
    {
        return $this->charge($amount, array_merge($options, [
            'customFields' => [
                'description' => $description,
            ],
        ]));
    }

提前感谢您给我的建议