Getting erro in pylab

I'm getting the following error:

    from matplotlib.pylab import *
  File
"/usr/lib/python2.4/site-packages/matplotlib/pylab.py",
line 709, in ?
    figimage.__doc__ = Figure.figimage.__doc__ + """
TypeError: unsupported operand type(s) for +:
'NoneType' and 'str'
"

Any ideas what it might be and how I can get around
it?

Thanks,

VJ