使用参数'（）'和关键字参数'{}'找不到[VIEW]的反转。尝试过0种模式：[]

Question

我收到错误NoReverseMatch at /。我需要了解导致此问题的原因以及如何解决此问题。

Reverse for 'sites' with arguments '()' and keyword arguments '{}' not found. 0 pattern(s) tried: []

这是我在Mezzanine的设置：

PROJECT_NAME /应用/模板/ index.html中：

<li class="dropdown">
          <a href="{% url "sites" %}">{% trans "Sites" %} <span class="caret"></span></a>
          <ul class="dropdown-menu">
            <li><a href="{% url "sites" %}">{% trans "All Sites" %}</a></li>
            <li><a href="{% url "sites_new" %}">{% trans "New Sites" %}</a></li>
            <li><a href="{% url "latest_entries" %}">{% trans "Latest Entries" %}</a></li>
          </ul>
    </li>

PROJECT_NAME /应用/ views.py：

def sites(request):
    return render(request, 'lists/sites.html')

def sites_new(request):
    return render(request, 'lists/sites_new.html')

def latest_entries(request):
    latest_entries = BlogPost.objects.all().filter(site_id=1, publish_date__lte=datetime.date.today())[:50]
    context = {'latest_posts': latest_posts}
    return render(request, 'lists/latest_entries.html', context)

PROJECT_NAME /应用/ urls.py：

urlpatterns = [
    url(r'^sites/$', views.sites, name='sites'),
    url(r'^sites/new/$', views.sites_new, name='sites_new'),
    url(r'^latest/$', views.latest_entries, name='latest_entries'),
]

PROJECT_NAME / urls.py：

urlpatterns += [
    url('^$', direct_to_template, {'template': 'index.html'}, name='home'), 
    url('^', include('mezzanine.urls')),
]