使用贝宝按钮角度指令时交易无效？

Question

我正在尝试将贝宝的angular指令用于贝宝按钮。这是我的代码：

<paypal-button
payment="paymentDetails.createPayment"
on-authorize="paymentDetails.executePayment"
ng-attr-style="paymentDetails.paypalButtonStyle"
commit="true"
env="sandbox"
style="position: absolute; bottom: 0;"
></paypal-button>

显示了该按钮，但是当我单击它时出现此错误：

This transaction is invalid. Please return to the 
recipient's website to complete your transaction using their regular checkout flow.

我尝试不使用指令，并且效果很好。

HTML代码：

<div id="paypal-button" style="position: absolute; bottom: 0;"></div>

控制器中的代码

$timeout(function() {
        paypal.Button.render({
            env: 'sandbox',
            commit: true,
            payment: createPayment,
            onAuthorize: executePayment,
            style: vm.paypalButtonStyle
        }, '#paypal-button');
    });

为什么指令方式无效？只是我提到了这一点： https://github.com/paypal/paypal-checkout/blob/master/docs/frameworks.md#angularjs-element