求助：好像是django配置URLS的问题，但不知道哪里错了，麻烦各位高手指教

我按照Django官网的例子写了第一个view，mysite/polls/views.py文件内容：

from django.http import HttpResponse

def index(request):

    return HttpResponse("Hello world. You're at the polls index.")

mysite/urls.py文件内容：

from django.conf.urls import patterns, include, url
from django.contrib import admin

admin.autodiscover()

urlpatterns = patterns('',
    url(r'^polls/', include('polls.urls')),
    url(r'^admin/', include(admin.site.urls)),
)

mysite/polls/urls.py文件内容

from django.conf.urls import patterns, url
from polls import views

urlpatterns = patterns('', 
    url(r'^$', views.index, name='index'), 
    )

运行server，并访问：http://localhost:8000/polls/

Page not found (404)
Request Method:     GET
Request URL:    http://localhost:8000/polls/

Using the URLconf defined in mysite.urls, Django tried these URL patterns, in this order:

   1. ^admin/

The current URL, polls/, didn't match any of these.

You're seeing this error because you have DEBUG = True in your Django settings file. Change that to False, and Django will display a standard 404 page.

在django的URLpattern列表中居然没有^polls，不知道啥原因，麻烦各位高手指教。