I have this plugin installed, however I dont seem to be able to enable it in a particular course I am building .

I can see the plugin in " manage enrol plugins ", it is visible and no longer greyed out ( after clicking on the "eye" icon ),

However when i go to the course I want to use it for as an enrolment method it doesn't appear in the " add method " drop down list ? 

Any advice on resources I could use to try to work out what is wrong would be greatly appreciated please ? 

I am using plugin version 2018092300 and I am using Moodle 3.1.6 (Build: 20170508)