Symfony2自定义Twig扩展-找不到类

我在添加Twig扩展时遇到问题。我得到以下错误：

ClassNotFoundException in appDevDebugProjectContainer.php line 317:
Attempted to load class "AppExtension" from namespace "HouseBundle'Twig".
Did you forget a "use" statement for another namespace?

我的代码：

/用户/站点/www/hoes/src/hoesBundle/Twig/AppExtension.php

<?php
namespace HouseBundle'Twig;
class AppExtension extends 'Twig_Extension
{
    public function getFilters()
    {
        return array(new 'Twig_SimpleFilter('price', array($this, 'priceFilter')),
    );

    public function priceFilter($number, $decimals = 0, $decPoint = '.', $thousandsSep = ',')
    {
        $price = number_format($number, $decimals, $decPoint, $thousandsSep);
        $price = '$'.$price;
        return $price;
    }
    public function getName()
    {
        return 'app_extension';
    }
}

/用户/站点/www/hoes/app/config/services.yml

services:
    app.twig_extension:
        class: HouseBundle'Twig'AppExtension
        tags:
            - { name: twig.extension }

任何帮助都将不胜感激。