偶尔500错误

WSGIScriptAlias / /home/rls/django_wsgi.py

import os, sys
sys.path.append('data/misc/django')
os.environ['DJANGO_SETTINGS_MODULE'] = 'rls.settings'

import django.core.handlers.wsgi

application = django.core.handlers.wsgi.WSGIHandler()

mod_wsgi (pid=4825): Exception occurred processing WSGI script '/home/rls/django_wsgi.py'.
Traceback (most recent call last):
File "/usr/lib/python2.5/site-packages/django/core/handlers/wsgi.py", line 230, in __call__
self.load_middleware()
File "/usr/lib/python2.5/site-packages/django/core/handlers/base.py", line 33, in load_middleware
for middleware_path in settings.MIDDLEWARE_CLASSES:
File "/usr/lib/python2.5/site-packages/django/utils/functional.py", line 276, in __getattr__
self._setup()
File "/usr/lib/python2.5/site-packages/django/conf/__init__.py", line 40, in _setup
self._wrapped = Settings(settings_module)
File "/usr/lib/python2.5/site-packages/django/conf/__init__.py", line 75, in __init__
raise ImportError("Could not import settings '%s' (Is it on sys.path? Does it have syntax errors?): %s" % (self.SETTINGS_MODULE, e))
ImportError: Could not import settings 'rls.settings' (Is it on sys.path? Does it have syntax errors?): No module named rls.settings