graphite-web error in fetch

I'm trying to configure graphite-web to read data but I got an exception

`
Internal Server Error: /graphite/render/
Traceback (most recent call last):
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/exception.py", line 41, in inner
response = get_response(request)
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 187, in _get_response
response = self.process_exception_by_middleware(e, request)
File "/usr/local/lib/python2.7/dist-packages/django/core/handlers/base.py", line 185, in _get_response
response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "/opt/graphite/webapp/graphite/render/views.py", line 121, in renderView
data.extend(evaluateTarget(requestContext, targets))
File "/opt/graphite/webapp/graphite/render/evaluator.py", line 14, in evaluateTarget
prefetchData(requestContext, pathExpressions)
File "/opt/graphite/webapp/graphite/render/datalib.py", line 255, in prefetchData
for result in STORE.fetch(pathExpressions, startTime, endTime, now, requestContext):
File "/opt/graphite/webapp/graphite/storage.py", line 100, in fetch
raise Exception('All fetches failed for %s' % (str(patterns)))
Exception: All fetches failed for [u'local.random.diceroll']
`