Not able to translate Pro Sites or other wpmudev plugins

Hi. I am trying to translate some of your plugins - but are not able to get it to work.

This is what I have done:

1. I have downloaded norwegian from here:

2. I renamed the file to psts-nb_NO since that is the language I am using (have tried with just psts-no also). I have downloaded and uploaded both .mo and .po files

3. I uploaded the file to the language folder inside Pro Sites pluginfolder.

What am I missing here? I have translated other plugins on the same site and those work OK.