munin plugin for nginx

[Grant]

I'm having some trouble getting the nginx plugin working for munin.
I've added the following to nginx config and restarted:

location /nginx_status {
        stub_status on;
        access_log   off;
        allow 127.0.0.1;
        deny all;
}

I've added the following munin config:

[nginx*]
env.url http://localhost/nginx_status

Unfortunately I still get:

# munin-run nginx_request
request.value U
# munin-run nginx_status
total.value U
reading.value U
writing.value U
waiting.value U

If I remove the allow/deny, I can browse to /nginx_status and I get:

Active connections: 13
server accepts handled requests
 15 15 16
Reading: 0 Writing: 1 Waiting: 12

What could be the problem?

- Grant