- Unsuitable environment or antenna placement causing noisy velocity data, so that the VBOX data never reaches 0.8 km/h.
- Onboard filtering has been used which may be smoothing the raw data so much that the exact point in time that the car reaches zero cannot be detected.
- The vehicle being tested is tall and has soft suspension. This can cause the velocity before the Rock Back to not go below 0.5 km/h. If this is the case, then look at the data in the graph screen to establish a minimum speed that the vehicle does reach before the rock back and apply this to the Report Generator test setup.