Django TemplateDoesNotExist

我建立了一个名为"mysite"的django项目.我的urls.py是

from django.conf.urls import patterns, include, url
from .views import WelcomeView
urlpatterns = patterns('',
    url(r'^$', WelcomeView.as_view(), name='welcome'),
)

我的views.py是:

from django.views import generic
class WelcomeView(generic.TemplateView):
    template_name = 'templates/welcome.html'  

目录结构是

+/home/mysite
    - manage.py
    - static
    + mysite
        - views.py
        - urls.py
        - settings.py
        - __init__.py
        + templates
            - welcome.html

当我跑:

python manage.py runserver

我的浏览器说:"TemplateDoesNotExist at templates/welcome.html".有人可以帮帮我吗？非常感谢 !