Look at the prompts in the app. This is most likely to happen if:
Didn't turn off the light
Handbrake not applied
Did not move the automatic transmission lever to the 'P' position
Didn't turn off the ignition
Do not close the door, trunk, hood.
Parked the car in a place with no GPS or GSM reception. Move the car to another location and try again.
If you still can't figure it out, call the Support Service, we will help.