why can not it set the state in the planning scene to the final state of the last plan?

In moveit tutorial at motion planning API section , 3 paths were generated. at each path it was claimed that the robot start from the end of previous path point. but when i run the tutorial's program at each path it was started from the initial positon. why does not following tutorial's command work? /* We will add more goals. But first, set the state in the planning scene to the final state of the last plan */ robot_state->setJointGroupPositions(joint_model_group, response.trajectory.joint_trajectory.points.back().positions);