If you are at the gate and your app is showing "Out of Range" there is a few things to check:
Make sure you have a internet connection (either building wi-fi or mobile is fine)
Check your bluetooth is enabled (and you have no other active bluetooth connections)
Location services are turned on
Close the app fully and re open it again
If you've changed these settings while at the gate, you may need to close the Parkable app to refresh your details.