I would have thought it would have to do with the car being immobilised though, whether it be because of the key or not. surely the key you are using disables the immobiliser as you would never be able to drive it :crackup:
Open the doors, take the handbrake off, push it 10-20 feet down the road and if RAC trackstar rings you, you know its working.
The RAC Trackstar unit utilises a GPS aerial and a mobile phone aerial - this will automatically phone the trackstar control centre if it detects movement when the engine is not running and has some wizardry to detect if the car is moving in a different direction to the way its facing.
They can also 'phone' the rac trackstar unit via its voice cli number to find out its exact location and speed.
Finally, you can ring RAC Trackstar customer support who will test the unit free of charge for you (basically they will ring it up and then verify if the device answers + tells the correct location). It is definitely worth doing this as my RAC Trackstar device still had the PIN number embedded into the SIM card so the mobile phone bit of it was inactive rendering the entire device useless.