GPS-data was not updated while moving and GPS_COUNT() did not respond as expected.
In most cases the result for x,y,z was -1,-1,-1
It was a serious problem until I found the following text on internet:
Then it was clear that changes can not be expected with small movements in your room.The Wi-Fi model of the iPad does not have an Assisted-GPS chip, but it can locate the user by using Wi-Fi triangulation.
This isn't quite as accurate as Assisted-GPS, but it is fairly accurate.
As a consequence I made a subroutine and a function to obtain reliable GPS-data.
The rest of this post has been removed. It is updated by the post "Update GPS via WiFi" on viewtopic.php?f=4&t=409