ERROR: Cannot locate node of type [ydlidar_ros_driver_node]

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Facts: ROS Melodic ; Ubuntu 18.04 ; YDLidar X2 Commands: roslaunch ydlidar_ros_driver X2.launch => ERROR roslaunch-logs

I real can NOT see where is a sign in the log for this error.

[roslaunch][INFO] 2020-12-10 11:21:10,246: Checking log directory for disk usage. Press Ctrl-C to interrupt [roslaunch][INFO] 2020-12-10 11:21:10,261: Done checking log file disk usage. Usage is <1GB. [roslaunch][INFO] 2020-12-10 11:21:10,262: roslaunch starting with args ['roscore', '--core'] [roslaunch][INFO] 2020-12-10 11:21:10,263: roslaunch env is {'ROS_DISTRO': 'melodic', 'MATE_DESKTOP_SESSION_ID': 'this-is-deprecated', 'XDG_GREETER_DATA_DIR': '/var/lib/lightdm-data/robert', 'PKG_CONFIG_PATH': '/opt/ros/melodic/lib/pkgconfig', 'XDG_RUNTIME_DIR': '/run/user/1000', 'XDG_CURRENT_DESKTOP': 'MATE', 'XDG_SESSION_TYPE': 'x11', 'LOGNAME': 'robert', 'USER': 'robert', 'ROS_PACKAGE_PATH': '/home/robert/ydlidar_ws/src:/opt/ros/melodic/share', 'XDG_VTNR': '7', 'HOME': '/home/robert', 'CMAKE_PREFIX_PATH': '/home/robert/ydlidar_ws/devel:/opt/ros/melodic', 'DISPLAY': ':0', 'SSH_AGENT_PID': '1573', 'LANG': 'de_DE.UTF-8', 'MANAGERPID': '1087', 'SHELL': '/bin/bash', 'XDG_SESSION_PATH': '/org/freedesktop/DisplayManager/Session0', 'XAUTHORITY': '/home/robert/.Xauthority', 'JOURNAL_STREAM': '9:31370', 'SESSION_MANAGER': 'local/robert-desktop:@/tmp/.ICE-unix/1166,unix/robert-desktop:/tmp/.ICE-unix/1166', 'XDG_DATA_DIRS': '/usr/share/mate:/usr/local/share:/usr/share:/var/lib/snapd/desktop', 'QT_QPA_PLATFORMTHEME': 'gtk2', 'LD_LIBRARY_PATH': '/home/robert/ydlidar_ws/devel/lib:/opt/ros/melodic/lib', 'QT_ACCESSIBILITY': '1', 'WINDOWID': '46137350', 'GTK_OVERLAY_SCROLLING': '0', 'ROS_LOG_FILENAME': '/home/robert/.ros/log/6c12844a-3ad1-11eb-b69d-b827eb67c271/roslaunch-robert-desktop-3673.log', 'PYTHONPATH': '/opt/ros/melodic/lib/python2.7/dist-packages', 'IM_CONFIG_PHASE': '1', 'ROS_MASTER_URI': 'http://localhost:11311', 'GPG_AGENT_INFO': '/run/user/1000/gnupg/S.gpg-agent:0:1', 'ROS_PYTHON_VERSION': '2', 'INVOCATION_ID': '615ba9b5dc5740b8ac95dda688a52391', 'PATH': '/opt/ros/melodic/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin', 'XDG_SESSION_DESKTOP': 'mate', 'ROS_VERSION': '1', 'QT_SCALE_FACTOR': '1', 'SSH_AUTH_SOCK': '/run/user/1000/keyring/ssh', 'TERM': 'xterm', 'ROS_ROOT': '/opt/ros/melodic/share/ros', 'GDMSESSION': 'mate', 'XDG_SEAT_PATH': '/org/freedesktop/DisplayManager/Seat0', 'DBUS_STARTER_BUS_TYPE': 'session', 'LESSOPEN': '| /usr/bin/lesspipe %s', 'XDG_SESSION_ID': 'c1', 'DBUS_SESSION_BUS_ADDRESS': 'unix:path=/run/user/1000/bus,guid=34380618ffb74db3e6d215df5fd1c79c', '_': '/opt/ros/melodic/bin/roscore', 'DESKTOP_SESSION': 'mate', 'LESSCLOSE': '/usr/bin/lesspipe %s %s', 'GTK_MODULES': 'appmenu-gtk-module:gail:atk-bridge:canberra-gtk-module', 'VTE_VERSION': '5202', 'UBUNTU_MENUPROXY': '1', 'OLDPWD': '/home/robert', 'DBUS_STARTER_ADDRESS': 'unix:path=/run/user/1000/bus,guid=34380618ffb74db3e6d215df5fd1c79c', 'GDM_LANG': 'de_DE', 'LANGUAGE': 'de_DE', 'SHLVL': '1', 'PWD': '/home/robert/Downloads/lidar', 'ROS_ETC_DIR': '/opt/ros/melodic/etc/ros', 'QT_AUTO_SCREEN_SCALE_FACTOR': '0', 'COLORTERM': 'truecolor', 'XDG_CONFIG_DIRS': '/etc/xdg/xdg-mate:/etc/xdg', 'LS_COLORS': 'rs=0:di=01;34:ln=01;36:mh=00:pi=40;33:so=01;35:do=01;35:bd=40;33;01:cd=40;33;01:or=40;31;01:mi=00:su=37;41:sg=30;43:ca=30;41:tw=30;42:ow=34;42:st=37;44:ex=01;32:*.tar=01;31:*.tgz=01;31:*.arc=01;31:*.arj=01;31:*.taz=01;31:*.lha=01;31:*.lz4=01;31:*.lzh=01;31:*.lzma=01;31:*.tlz=01;31:*.txz=01;31:*.tzo=01;31:*.t7z=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.dz=01;31:*.gz=01;31:*.lrz=01;31:*.lz=01;31:*.lzo=01;31:*.xz=01;31:*.zst=01;31:*.tzst=01;31:*.bz2=01;31:*.bz=01 ... (more)