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

Periodically, I get next error:

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

I do not understand quickly why my code is not works. Well, I write down this notes. Check list:

1. Include urls.py of app to project urls.py

urlpatterns = patterns('',
    ...
    url(r'^my_app/', include('my_app.urls')),
    ...
)

2. Include url to urls.py of app:

urlpatterns = patterns('',
    url(r'^my-url-name/(?P<my_object_id>\d+)/$', my_app.views.my_view, name='my_url_name'),
)

3. Add required arguments to urls.py

urlpatterns = patterns('',
    url(r'^my-url-name/(?P<my_object_id>\d+)/$', my_app.views.my_view, name='my_url_name'),
)

4. Add required arguments with call 'url' function in template or 'reverse' function in python code

# in template.html
<a href="{% url 'my_url_name' my_object_id %}">Do something</a>

# in python code
reverse('my_url_name', args=(my_object_id, ))

If your view doesn't provide arguments (such as my_object_id), then check the first two steps only.