problem with polar plots and thetagrids

Dears, I'm trying to change the labels of a polar plot I have inside a
wxpython app, but keep getting errors...

this is a snippet of the code:

#class for the second page of the notebook
class PlotPanel(wx.Panel):
  def __init__(self, parent):
    wx.Panel.__init__(self, parent)

    box1 = wx.BoxSizer(wx.VERTICAL)
    st1 = wx.StaticText(self, -1, 'Plot')
    box1.Add(st1, 0, wx.RIGHT, 8)
    box3 = wx.BoxSizer(wx.VERTICAL)

    self.figure = Figure(figsize=(6,6))#
    self.canvas = FigureCanvas(self, -1, self.figure)
    self.axes = self.figure.add_axes([0.1, 0.1, 0.8, 0.8],projection='polar')

    pylab.thetagrids( range(0,360,45), ('E', 'NE', 'N','NW', 'W', 'SW',
'S', 'SE') )

    box3.Add(self.canvas, 1, wx.LEFT|wx.TOP|wx.GROW)

    box1.Add(box3,1, wx.EXPAND)

and these are the error msgs:

Traceback (most recent call last):
  File "", line 184, in <module>
  File "/usr/lib/python2.5/site-packages/wx-2.8-gtk2-unicode/wx/",
line 7912, in __init__
  File "/usr/lib/python2.5/site-packages/wx-2.8-gtk2-unicode/wx/",
line 7487, in _BootstrapApp
    return _core_.PyApp__BootstrapApp(*args, **kwargs)
  File "", line 179, in OnInit
    self.frame=MyFrame(None, -1, 'PyStereo', size=(800,600))
  File "", line 120, in __init__
    self.right_panel = PlotPanel(splitter) # right panel, where stats are shown
  File "", line 70, in __init__
    pylab.thetagrids( range(0,360,45), ('E', 'NE', 'N','NW', 'W',
'SW', 'S', 'SE') )
  File "/usr/lib/python2.5/site-packages/matplotlib/", line
1092, in thetagrids
    raise RuntimeError('rgrids only defined for polar axes')
RuntimeError: rgrids only defined for polar axes




Carlos Henrique Grohmann - Geologist D.Sc.
a.k.a. Guano - Linux User #89721
ResearcherID: A-9030-2008
carlos dot grohmann at gmail dot com
"Good morning, doctors. I have taken the liberty of removing Windows
95 from my hard drive."
--The winning entry in a "What were HAL's first words" contest judged
by 2001: A SPACE ODYSSEY creator Arthur C. Clarke

Can’t stop the signal.