Language translation

I’m trying to get this lovely plugin working in Dutch. I’ve already the documention on the translation files (po and mo files in uploads/espresso/languages folder) and was under the impression that “Once the files are uploaded, as long as WordPress has been updated to accept a new language, Event Espresso will follow suit.” …but it’s not doing it for me.

My WordPress is 4.0.1 in Dutch. Thanks in advance.

https://www.ads-software.com/plugins/event-espresso-free/