Error with PYLAB netplotlib library

Hello everyone, I tried to install matplotlib but I am having some problems:

after installing all the necessary prerequisites (cairo, pycairo, pygo...,
pygtk), I installed MATPLOTLIB as:

python setup.py build
python setup.py install

but when I finally try to use it by calling >>> from pylab import *
I receive the followinbg error:

Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/cdat/lib/python2.4/site-packages/pylab.py", line 1, in ?
    from matplotlib.pylab import *
ImportError: No module named matplotlib.pylab

I hope anyone can help me,

thanks

simone