pybullet.error: GetBasePositionAndOrientation failed.

I used pybullet to create a custom environment class named MultiTrackAviary, and I want to initialize this class, as follows: env = MultiTrackAviary()
env_evaluate = MultiTrackAviary()

However, the following error occurred： Traceback (most recent call last): File "F:\Code\gym-pybullet-drones\gym_pybullet_drones\examples\test2.py", line 6, in env_evaluate = MultiTrackAviary() File "F:\Code\gym-pybullet-drones\gym_pybullet_drones\envs\MultiTrackAviary.py", line 71, in init super().init(drone_model=drone_model, File "F:\Code\gym-pybullet-drones\gym_pybullet_drones\envs\BaseRLAviary.py", line 79, in init super().init(drone_model=drone_model, File "F:\Code\gym-pybullet-drones\gym_pybullet_drones\envs\BaseAviary.py", line 227, in init self._updateAndStoreKinematicInformation() File "F:\Code\gym-pybullet-drones\gym_pybullet_drones\envs\BaseAviary.py", line 573, in _updateAndStoreKinematicInformation self.target_pos[:], _ = p.getBasePositionAndOrientation(self.target_id, physicsClientId=self.CLIENT) pybullet.error: GetBasePositionAndOrientation failed.

Can someone help me？