I did read about the GKContact plugin and did as was written there.... i downloaded it from the Creativity template files and installed it.
Then i noticed something weird, the text from the language files wasnt used, there were just the labels (for instance: PLG_GKCONTACT_NAME_FIELD).
I checked if the language files were installed and they were in administrator/language/en-GB.
I tried making copies and adjust the file names for NL, but then they still not worked.
What am i doing wrong?