Static files load problem Django 1.9

Fri Apr 15 08:13:01 EDT 2016

I have got a problem with static files regarding Django 1.9. These files
are (js,css) in the standard folder static, inside project folder
directory. I got an error Http 404 that can not be loaded.
Project folder / static / css / several files *.css
 /static / js / several files *.js
 several_apps
i have executed the python manage.py collectstatic
settings.py
STATIC_URL = '/static/'
STATIC_ROOT = os.path.join(BASE_DIR, "static")
STATICFILES_DIRS = (
 os.path.join(BASE_DIR, 'static'),
)
and of course as INSTALLED_APPS
'django.contrib.staticfiles',
Sorry for my template (at the beginning of my work):
{% load staticfiles %}
<html>
 <head>
 <link rel="stylesheet" href="{% static 'css/jquery-ui.css' %}">
 <link rel="stylesheet" href="{% static 'css/ui.jqgrid.css' %}">
 <script src="{% static 'js/jquery-1.11.0.min.js' %}"
type="text/javascript"> </script>
 <script src="{% static 'js/jquery.jqGrid.min.js' %}"
type="text/javascript"> </script>
 <script src="{% static 'js/grid.locale-el.js' %}"
type="text/javascript"> </script>
 <script src="{% static 'js/category.js' %}" type="text/javascript">
</script>
 </head>
 <body>
 <table id="grid"></table>
 <div id="pager"></div>
 </body>
</html>
but i am afraid the problem lies in urls.py (i do not know what to do)
http://127.0.0.1:8000/static/css/file_name (in the firebug network) but i
can not open it directly via server.
urls.py
urlpatterns = [
 url(r'^admin/', admin.site.urls),
 url(r'^hello/','category.views.hello'),
]
Any kind of help would be convenient to me?
Kind Regards
Kostas Asimakopoulos