I am unable to get rosmsg show num

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http://wiki.ros.org/ROS/Tutorials/Cre...

In the above tutorial whenever i trying to get rosmsg show num i will face this error in bash

**glv13@GLV-Inspiron-N4010:~/catkin_ws/src/my_first_package$ rosmsg show num
Traceback (most recent call last):
  File "/opt/ros/kinetic/bin/rosmsg", line 35, in <module>
    rosmsg.rosmsgmain()
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmsg/__init__.py", line 754, in rosmsgmain
    sys.exit(rosmsg_cmd_show(ext, full, command))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmsg/__init__.py", line 621, in rosmsg_cmd_show
    found_msgs = list(rosmsg_search(rospack, mode, arg))
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmsg/__init__.py", line 565, in rosmsg_search
    for p, path in iterate_packages(rospack, mode):**
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmsg/__init__.py", line 541, in iterate_packages
    package_paths = _get_package_paths(p, rospack)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosmsg/__init__.py", line 554, in _get_package_paths
    results = find_in_workspaces(search_dirs=['share'], project=pkgname, first_match_only=True, workspace_to_source_spaces=_catkin_workspace_to_source_spaces, source_path_to_packages=_catkin_source_path_to_packages)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/catkin/find_in_workspaces.py", line 143, in find_in_workspaces
    source_path_to_packages[source_path] = find_packages(source_path)
  File "/usr/lib/python2.7/dist-packages/catkin_pkg/packages.py", line 89, in find_packages
    packages = find_packages_allowing_duplicates(basepath, exclude_paths=exclude_paths, exclude_subspaces=exclude_subspaces, warnings=warnings)
  File "/usr/lib/python2.7/dist-packages/catkin_pkg/packages.py", line 150, in find_packages_allowing_duplicates
    xml, filename=filename, warnings=warnings)
  File "/usr/lib/python2.7/dist-packages/catkin_pkg/package.py", line 552, in parse_package_string
    _get_node_attr(node, 'email')
  File "/usr/lib/python2.7/dist-packages/catkin_pkg/package.py", line 727, in _get_node_attr
    raise InvalidPackage('The "%s" tag must have the attribute "%s"' % (node.tagName, attr))
catkin_pkg.package.InvalidPackage: The "maintainer" tag must have the attribute "email"**