[Marttt]

Well I don't know, you may have some error log, or you are not as admin (z root) in the server.

Without errors the best I can advice you is to do a clean install.
Note: I'm using windows and listen server so maybe is a OS problem.

Try to remove all plugins and test just this one as standalone. Maybe something is messing up with the Admin menu, depending on the order.

Anyway if the plugin doesn't show up in the "sm plugins list" console probably didn't load.

Also try to take the .sp file and compile by yourself and then paste on the plugins folder, maybe is something related to the SM version in the forum vs your server version.