The VIN or part number that the tuner is currently locked to does not match the one that it is reading off the PCM. Our devices can only tune 1 vehicle at a time.
The tuner could be locked to another vehicle or the PCM in the vehicle may have been flashed by a dealership or local shop after the tune was installed, thus erasing the tune off of the ECM. If this is the case, current tuners including the GT's can be reset over the phone by calling Sales. There may be a fee associated with the reset.