Renaming group - error

I have a new Dolphin installation and decided to rename some groups. Whatever I try each groupname is shown as something like this: 85989368aac82798732. I decided to rename this gibberish but all I get is renaming error.

Anyone?  

Welke versie van Dolphin?
Had je al groepen aangemaakt? zo ja dan moet hernoemen geen probleem zijn. Getest in versie 6.1.4 

je mag me anders wel even mailen, ik zit in Groningen