roslaunch报错

Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/__init__.py", line 227, in main
    args = rlutil.resolve_launch_arguments(args)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/rlutil.py", line 92, in resolve_launch_arguments
    resolved = roslib.packages.find_resource(args[0], args[1])
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslib/packages.py", line 499, in find_resource
    pkg_path = rospack.get_path(pkg)
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 205, in get_path
    self._update_location_cache()
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 188, in _update_location_cache
    list_by_path(self._manifest_name, path, cache)
  File "/usr/lib/python2.7/dist-packages/rospkg/rospack.py", line 71, in list_by_path
    root = ElementTree(None, os.path.join(d, PACKAGE_FILE))
  File "/usr/lib/python2.7/xml/etree/ElementTree.py", line 611, in __init__
    self.parse(file)
  File "", line 38, in parse
ParseError: no element found: line 1, column 0

原因：CMakeList.txt文件以及package文件为空