Mod_python error: "PythonHandler mod_python.psp"

Traceback (most recent call last):

  File "/usr/lib/python2.4/site-packages/mod_python/apache.py", line 299, in HandlerDispatch
    result = object(req)

  File "/usr/lib/python2.4/site-packages/mod_python/psp.py", line 297, in handler
    p.run()

  File "/usr/lib/python2.4/site-packages/mod_python/psp.py", line 208, in run
    exec code in global_scope

  File "/var/www/media.mysimplecast.com/htdocs/current/index.psp", line 72, in ?

  File "/var/www/media.mysimplecast.com/htdocs/current/index.psp", line 60, in main

  File "/var/www/media.mysimplecast.com/include/mysimplecast.py", line 233, in url
    return os.path.join( self.customer.get_file_url_dir(), self.file_name())

  File "/var/www/media.mysimplecast.com/include/mysimplecast.py", line 175, in get_file_url_dir
    return os.path.join( '/', self.get_file_dir() )

  File "/var/www/media.mysimplecast.com/include/mysimplecast.py", line 167, in get_file_dir
    check_dir( self.get_file_fs_dir() )

  File "/var/www/media.mysimplecast.com/include/mysimplecast.py", line 85, in check_dir
    os.mkdir( dir )

OSError: [Errno 13] Permission denied: '/var/www/demo.mysimplecast.com/htdocs/files/5000'