Opencart 2.1.0.2-确认订单按钮文本不显示

Question

升级到PHP 7后，确认订单按钮不显示。Opencart 2.1.0.2

似乎我已经将Centos 7服务器升级到PHP 7，现在opencart中的这种付款方式与更改不符。我已经从“确认订单”按钮中丢失了文字。

<?php
class ControllerPaymentDpdCod extends Controller {
    protected $_data = '';
    public function index() { 
        $this->_data['button_confirm'] = $this->language->get('button_confirm');

        $this->_data['continue'] = $this->url->link('checkout/success');
        $this->_data['text_loading'] = $this->language->get('text_loading');
        if (file_exists(DIR_TEMPLATE . $this->config->get('config_template') . '/template/payment/dpd_cod.tpl')) {
            return $this->load->view($this->config->get('config_template') . '/template/payment/dpd_cod.tpl', $this->_data);
        } else {
            return $this->load->view('default/template/payment/dpd_cod.tpl', $this->_data);
    }
}

    public function confirm() {
        if ($this->session->data['payment_method']['code'] == 'dpd_cod') {
            $this->load->model('checkout/order');    
            $this->model_checkout_order->addOrderHistory($this->session->data['order_id'], $this->config->get('cod_order_status_id'));
        }
    }
}

我可以在上面的代码中进行哪些更改？ 谢谢