I found a translation error in the Skype for Business chat window. When a new message arrives but you need to scroll down to see it, there is a message notifying the user that there is 1 NEUE NACHRICHT, i.e. 1 NEW MESSAGE, with next to it a button saying GELESEN in German - which means READ but as a past participle, as in I HAVE READ THIS MESSAGE. It should rather be LESEN though - which is the infinitive form as in TO READ or PLEASE READ, used for CTAs. So GELESEN should be changed to LESEN in this context. Please find a screenshot attached.
