roslaunch panda_moveit_config demo.launch not working

edit

i am a beginner with ROS and Moveit. I wanted to do Movit tutorial, I did all Instalation and i tried the first tutorial : MoveIt Quickstart in RViz (http://docs.ros.org/en/melodic/api/mo...). It works well. Then i tried the second tutorial : Move Group C++ Interface (http://docs.ros.org/en/melodic/api/mo...) and it didn't work. The Problem was that when i run this : roslaunch panda_moveit_config demo.launch i see Rviz running but i couldnt open it. even if i launch this file in a second Shell: roslaunch moveit_tutorials move_group_interface_tutorial.launch Could you please help me? Thank you