I work closely with developpers on this plugin, I’ll try to help you.
First thing to check is the version. Get the last version according to your Graylog version:
Wizard Plugin Version
Graylog Version
4.4.x
4.3.x
4.3.x
4.2.x
4.2.x
4.2.x
4.1.x
4.2.x
4.0.x
4.1.x
3.3.x
3.3.x
3.2.x
3.2.x
3.1.x
3.0.x
3.0.x
3.0.x
2.0.x
2.5.x
1.1.x
2.5.x
1.0.0
2.4.x
Which Graylog version are you using ?
Then you should check unix permissions on /usr/share/graylog-server/plugin.
The graylog user must have the read right.
If you change something, restart the Graylog service. It doesn’t take a while, you should see result immediately.
Finally you should check server.log, you could have more details about errors.