python django 访问静态文件出现404或500错误

import os
PROJECT_ROOT = os.path.dirname(__file__)

DEBUG = True

STATIC_URL = '/static/'

STATICFILES_DIRS = (

  os.path.join(PROJECT_ROOT, 'static'),
)

STATICFILES_FINDERS = (
  'django.contrib.staticfiles.finders.FileSystemFinder',
  'django.contrib.staticfiles.finders.AppDirectoriesFinder',
)

<VirtualHost *:80>
   ServerName www.mydjangosite.com
   ServerAlias mydjangosite.com
   ServerAdmin fake@mydjangosite.com

   DocumentRoot /path/to/mydjangosite
   <Directory /path/to/mydjangosite>
       Options FollowSymLinks
       AllowOverride None
       Order allow,deny
       allow from all
   </Directory>

   Alias /static/ /path/to/mydjangosite/static/
   <Directory /path/to/mydjangosite/static>
       Order allow,deny
       allow from all
   </Directory>

   # The following installs the Django WSGI app
   WSGIDaemonProcess www.mydjangosite.com processes=2 threads=15 display-name=%{GROUP}
   WSGIProcessGroup www.mydjangosite.com
   WSGIScriptAlias / /path/to/mydjangosite/wsgi.py

</VirtualHost>