django1.6.11 管理页面的中文问题

使用环境如下： osx10.9.2 python 2.7 mysql 5.5.29 django 1.6.11 在127.0.0.1/admin打开什么都正常，但是在settings.py中添加'django.middleware.locale.LocaleMiddleware',后，；将django重新启动(sudo python manage.py runserver 80)后，显示的还是英文，恳请指出我哪个环节出的问题，应该怎样修改？谢谢！

settings.py部分配置：

INSTALLED_APPS = (
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'books',
)

MIDDLEWARE_CLASSES = (
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.locale.LocaleMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
)

ROOT_URLCONF = 'mysite.urls'

LANGUAGE_CODE = 'en-us'

TIME_ZONE = 'Asia/Shanghai'

USE_I18N = True

USE_L10N = True

USE_TZ = True

STATIC_URL = '/static/'