Exception in Tkinter callback

While using PyPlot.jl I am receiving the following error:

Exception in Tkinter callback
Traceback (most recent call last):
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/lib-tk/Tkinter.py", line 1541, in __call__
return self.func(*args)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/lib-tk/Tkinter.py", line 592, in callit
func(*args)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.py", line 323, in idle_draw
self.draw()
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/backends/backend_tkagg.py", line 304, in draw
FigureCanvasAgg.draw(self)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/backends/backend_agg.py", line 430, in draw
self.figure.draw(self.renderer)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
return draw(artist, renderer, *args, **kwargs)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/figure.py", line 1295, in draw
renderer, self, artists, self.suppressComposite)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
a.draw(renderer)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
return draw(artist, renderer, *args, **kwargs)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/axes/_base.py", line 2399, in draw
mimage._draw_list_compositing_images(renderer, self, artists)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/image.py", line 138, in _draw_list_compositing_images
a.draw(renderer)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/artist.py", line 55, in draw_wrapper
return draw(artist, renderer, *args, **kwargs)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/collections.py", line 321, in draw
self._offset_position)
File "/Users/ian/.julia/v0.6/Conda/deps/usr/lib/python2.7/site-packages/matplotlib/backends/backend_agg.py", line 120, in draw_path_collection
return self._renderer.draw_path_collection(*kl, **kw)
TypeError: Cannot cast array data from dtype('S3') to dtype('float64') according to the rule 'safe'
PyObject Text(0.5,1,u'Massa')