Bug from follow_target_with_rmpflow.py

Hi,
I just downloaded Isaac Sim 4.1.0 from omniverse and are trying to learn about the Isaac Sim workflows. But when I tried to run the follow_target_with_rmpflow.py script (by inputting ./python.sh standalone_examples/api/omni.isaac.franka/follow_target_with_rmpflow.py in the terminal)following the instruction in Isaac Sim Workflows — Omniverse IsaacSim latest documentation, I couldn’t move the target prim of Franka by selecting it in the viewport.
The interface can be opened and I can zoom in or orbit around Franka. I can alos select Franka, but every time I try to move it by moving the target prim, the program just suddenly ends and an python exception is raised in the terminal saying that: Failed to get DOF positions from backend.

Solved. I was moving Franka directly instead of the target prim, causing errors from physical engine.