Thanks verry much. The online decoder gave me the information that both Network Keys were not correct, INVALID MIC.
Looking around at Antratek found that the prescription was not correct and that you should ask for a valid AppKey for your sensor. Antratek responded verry fast with a valid AppKey. That dit the trick.
Now the tabs sebsor works correct.
Your advice was a big help for me, and now i now a lot more about DevEUI, AppEUI and AppKey.