ImportError：没有名为sekizai的模块

我已根据文档安装了所有三个依赖项（Python 2.6、2.7、3.2或更高版本。Django1.2.7或更高版本。django-classy-tags0.3.1或更高版本），但是当我在INSTALLED_APPS设置中添加“ sekizai”时，并执行“ manage.py runserver”，它将向我报告“ ImportError：没有名为sekizai的模块”。

我在settings.py中的内容：

    # Application definition

    INSTALLED_APPS = (
        'django.contrib.admin',
        'django.contrib.auth',
        'django.contrib.contenttypes',
        'django.contrib.sessions',
        'django.contrib.messages',
        'django.contrib.staticfiles',
        'mptt',
        'hw',
        'useraccess',
        'proxy',
        'compressor',
        'sekizai',
    )

    MIDDLEWARE_CLASSES = (
        'django.contrib.sessions.middleware.SessionMiddleware',
        'django.middleware.common.CommonMiddleware',
        'django.middleware.csrf.CsrfViewMiddleware',
        'django.contrib.auth.middleware.AuthenticationMiddleware',
        'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
        'django.contrib.messages.middleware.MessageMiddleware',
        'useraccess.middleware.VisitCollectMiddleware',
        'django.middleware.clickjacking.XFrameOptionsMiddleware',

    )

TEMPLATE_CONTEXT_PROCESSORS = (
    'django.contrib.auth.context_processors.auth',
    'django.core.context_processors.i18n',
    'django.core.context_processors.request',
    'django.core.context_processors.media',
    'django.core.context_processors.static',
    'hw.context_processors.user_info',
    'hw.context_processors.login_form',
    'hw.context_processors.get_all_user',
    'sekizai.context_processors.sekizai',
)