Multilingual plugin not working.

After hours and hours of testing things out i am still stuck. I am tryin to add support for multiple languages in a plugin. I tried all the official documentation steps and more but i simply can’t get it to work. I am hoping someone got a quick fix to prevent me from wasting another day.

In the file below i used a plugin template and Locotranslate to quickly make a failing translation example. My WordPress is set to Dutch language and it’s a fresh installment (4.4.2) with just locotranslate and this plugin installed.

http://www.filedropper.com/test123