Adding a 3D camera to a robot arm(ur5) in URDF for Rviz and Gazebo

Hi all, I am following boor Mastering ROS for Robotics Programmin and I am trying to add a 3D camera above my UR5 arm in urdf. But after I modified the ur5.urdf.xacro file by adding . Thank you so much!!!! [Please find the details of my problem with this link](https://github.com/qboticslabs/mastering_ros/issues/37)