Loading External Modules to Metasploit

I am having an extremely difficult time trying to load external modules to metasploit. I read the following github guide on how to do it: https://github.com/rapid7/metasploit-framework/wiki/Loading-External-Modules. I also followed along with the example they provided, tested it out and was able to load the module with no problem.

In the example, it tells you to download a 'test' module and place it in /.msf4/modules/exploits/test/test_module.rb, then load the module in msf. I had no problem doing this.

For whatever reason though, when I take the EXACT same steps to load another module, it fails. At first I figured it must have something to do with the path I'm creating so I moved my module to the 'test' folder I created during the example and tried calling the module in msf but again, it fails to find it. I have reloaded_all to update my modules several times and even stopped and restarted msf. Sill no luck.

I am literally taking the exact same steps I did during the example I was successful with.

In addition, the modules that are already supposed to be loaded in msf, arent. For example, I was looking for an exploit for a WordPress NextGEN Gallery Directory Read Vulnerability. A exploit module already comes with metasploit. The path is supposed to be auxiliary/scanner/http/wp_nextgen_galley_file_read, yet when I type 'use auxiliary/scanner/http/wp_nextgen_galley_file_read, it fails to locate the module. Wth??

Your help is much appreciated!