rqt_nav_view get a float division error

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I was just click on set pose and set goal and got this error. How is this panel used? Set goal and set pose work on the rviz main panel.

viki:~$ rosrun rqt_nav_view rqt_nav_view 
Traceback (most recent call last):
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_nav_view/nav_view.py", line 403, in mouseReleaseEvent
    map_p, quat = self.draw_position(e)
  File "/opt/ros/hydro/lib/python2.7/dist-packages/rqt_nav_view/nav_view.py", line 354, in draw_position
    u = (v[0]/mag, v[1]/mag)
ZeroDivisionError: float division by zero