This is what the Iphone screen shows, but nowhere to unlock.
On the webpage of Geo there are no zones to be seen, so there is nothing to unlock !

You are almost next to the fence of Limburg airport and you should be glad the system won't let you take off!
If you think you are authorized to fly in an area called by DJI 'Authorization Zone' you need to have a registered account with DJI.
http://www.dji.com/flysafe/geo-system
If you look at AirMap you will see that there are more restrictions applied to that airspace.

You wanna go somewhere else - bad place to fly.

Thanks for your sound advice.
I always am very cautious because of the area.
I do have an registered account and flew here before around my own business buildings with an dji authorisation.
But now the map is empty. My question is why ??

Something seems to be messed up on DJI side with Belgium.
If you look at http://www.dji.com/flysafe/geo-map no zones at all are shown for Belgium.
If this map matches the data provided through NFZ updates you shouldn't be seeing anything on your map, not even the yellow warning zone.
So it seems to be a mess for Belgium at this point.

Thanks a lot Eric for pointing this out. When I switch to another country all the zones are there, so it must be a problem with the Belgian zones as a whole. I'send an email to flysafe@dji.com, we'll see.

The friendly people at flysafe response :

Thank you for contacting DJI.

You can check the restricted zone via: http://www.dji.com/flysafe/geo-map
To unlock a restricted zone for the aircraft, please visit this link and submit an unlocking request.
http://www.dji.com/flysafe/geo-system/individual-unlock

Kindly note: at present, DJI approves a maximum unlocking radius of 30 kilometers, for a maximum period of 3 months.
For special requests in excess of these limits, i will forward all the documents to our supervisor for further approval.

The serial number you entered during the unlocking process should be aircraft's flight controller's SN which can be found at DJI Go app's About page beginning with 0.

If it is urgent, after you submit a request, please offer me its tracking number or the email address entered so we will unlock the aircraft in our server as soon as possible.

If there is any further question, please feel free to contact us. We're always here to help.
Thanks for choosing DJI. Have a nice day!

I would recommend you to re-install the APP and the check the map again. For unlock issue, our colleagues will take care of it.