Prearm bit never went true while using autotest

I have implemented a custom mode to track and land on a moving target. I am trying to use the existing autotest feature in ardupilot codebase to test my code for different scenarios. However, when a test gets completed and next test is getting called I am getting this error (Prearm bit never went true)

In each test I am testing whether the copter is tracking and landing on the target for different target trajectories and velocities

Should I be restarting my sitl in every test case since I am disarming the motors and landing?