error message

Traceback (most recent call last):
  File "/usr/lib/python3.5/tkinter/__init__.py", line 1562, in __call__
    return self.func(*args)
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_tkagg.py", line 280, in resize
    self.show()
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_tkagg.py", line 351, in draw
    FigureCanvasAgg.draw(self)
  File "/usr/lib/python3/dist-packages/matplotlib/backends/backend_agg.py", line 464, in draw
    self.figure.draw(self.renderer)
  File "/usr/lib/python3/dist-packages/matplotlib/artist.py", line 63, in draw_wrapper
    draw(artist, renderer, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/matplotlib/figure.py", line 1150, in draw
    self.canvas.draw_event(renderer)
  File "/usr/lib/python3/dist-packages/matplotlib/backend_bases.py", line 1815, in draw_event
    self.callbacks.process(s, event)
  File "/usr/lib/python3/dist-packages/matplotlib/cbook.py", line 549, in process
    proxy(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/matplotlib/cbook.py", line 416, in __call__
    return mtd(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/matplotlib/animation.py", line 831, in _start
    self._init_draw()
  File "/usr/lib/python3/dist-packages/matplotlib/animation.py", line 1490, in _init_draw
    self._draw_frame(next(self.new_frame_seq()))
  File "/usr/lib/python3/dist-packages/matplotlib/animation.py", line 1512, in _draw_frame
    self._drawn_artists = self._func(framedata, *self._args)
  File "ESP10_Draft_V046-large_changes.py", line 966, in animate
    a.plot(SLgraphDataTime, SLgraphData)
  File "/usr/lib/python3/dist-packages/matplotlib/__init__.py", line 1894, in inner
    return func(ax, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/matplotlib/axes/_axes.py", line 1407, in plot
    self.add_line(line)
  File "/usr/lib/python3/dist-packages/matplotlib/axes/_base.py", line 1787, in add_line
    self._update_line_limits(line)
  File "/usr/lib/python3/dist-packages/matplotlib/axes/_base.py", line 1809, in _update_line_limits
    path = line.get_path()
  File "/usr/lib/python3/dist-packages/matplotlib/lines.py", line 989, in get_path
    self.recache()
  File "/usr/lib/python3/dist-packages/matplotlib/lines.py", line 676, in recache
    x = np.asarray(xconv, np.float_)
  File "/usr/lib/python3/dist-packages/numpy/core/numeric.py", line 531, in asarray
    return array(a, dtype, copy