Django函数不返回HTML页面

我正在我的网站上添加分页。这是我的职责:

视图。py公司

def ProductList(request, category_slug=None, page_number=1):
  content = {}
  category = None
  categories = Category.objects.all()
  products = Product.objects.filter(available=True)
  if category_slug:
      category = get_object_or_404(Category, slug=category_slug)
      products = products.filter(category=category)
  current_page = Paginator(products, 2)
  content['category'] = category
  content['categories'] = categories
  content['products'] = current_page.page(page_number)
  return render(request, 'product/list.html', content)

URL。py公司

urlpatterns = [
    url(r'^$', views.ProductList, name='ProductList'),
    url(r'^page/(\d+)/$', views.ProductList, name='ProductList'),
    url(r'^(?P<category_slug>[-\w]+)/$', views.ProductList, name='ProductListByCategory'),
    url(r'^(?P<id>\d+)/(?P<slug>[-\w]+)/$', views.ProductDetail, name='ProductDetail'),

]

但每次我尝试获取下一页时,都会看到以下错误:

Page not found (404)
Request Method:     GET
Request URL:    http://127.0.0.1:8000/page/2/
Raised by:  shop.views.ProductList

我真的不明白我做错了什么。非常感谢。