[matplotlib-devel] log on a bar chart

Hi all,
anytime when requesting semilogy() on bar or hist chart, following error
occurs:
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/backends/backend_qtagg.py", line 161,
in print_figure
 **kwargs )
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/backends/backend_agg.py", line 456,
in print_figure
 self.draw()
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/backends/backend_agg.py", line 392,
in draw
 self.figure.draw(renderer)
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/figure.py", line 569, in draw
 for a in self.axes: a.draw(renderer)
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/axes.py", line 1155, in draw
 a.draw(renderer)
 File "/usr/lib/python2.5/site-packages/matplotlib-
0.90.0-py2.5-linux-i686.egg/matplotlib/patches.py", line 215, in draw
 tverts = self.get_transform().seq_xy_tups(verts)
ValueError: Cannot take log of nonpositive value
I am sure that there is no negative value (just some zeros - this could be
the problem)
Anybody have an idea how to solve it?