Custom Munin plugin won't report - plugins

Question

I've built my first Munin plugin to give us the size of our Redis queue, but it won't report for some reason. Every other plugin on the node, including other Redis-centric plugins work fine.
Here's the plugin code:
#!/bin/sh
case $1 in
config)
cat <<'EOM'
multigraph redis_queue_size
graph_title Redis Queue Size
graph_info The size of Redis queue
graph_category redis
graph_vlabel Messages
redisqueue.label redisqueue
redisqueue.type GAUGE
redisqueue.min 0
EOM
exit 0;;
esac
queuelength=`redis-cli llen mykeyname`
printf "redisqueue.value "
echo $queuelength
The plugin is in /usr/share/munin/plugins/redis_queue_
The plugin is symlinked to /etc/munin/plugins/redis_queue_
I made sure to restart the service
$ sudo service munin-node force-reload
If I run sudo munin-run redis_queue_ I get the correct output:
redisqueue.value 1567595
If I run munin-node-config I get the following:
redis_queue_ | yes |
If I connect to the instance from the master using telnet to fetch the plugin, I get:
$ telnet 10.101.21.56 4949
Trying 10.101.21.56...
Connected to 10.101.21.56.
Escape character is '^]'.
# munin node at redis01.example.com
fetch redis_queue_
redisqueue.value 1035336
The master shows an empty graph for it, but the "last updated" time isn't increasing. I initially had the plugin configured a little differently (it wasn't producing good output) so all the values are -nan. Once I fixed the output, I expected the plugin to start working, but all efforts have failed.
Everything looks right, but yet still no values in the graph.
Edit: Munin v1.4.6