import problem

Hi,
I installed matlibplot without any problems but when I tried to try it I got that error with the import:
>>> from matplotlib.matlab import *
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "matplotlib/matlab.py", line 133, in ?
    from axes import Axes
  File "matplotlib/axes.py", line 9, in ?
    from artist import Artist
  File "matplotlib/artist.py", line 4, in ?
    from transforms import identity_transform
  File "matplotlib/transforms.py", line 180, in ?
    from _transforms import Value, Point, Bbox, Affine
ImportError: No module named _transforms
>>> from matplotlib.matlab import *
>>> plot([1,2,3,4])
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
NameError: name 'plot' is not defined

It is weird because it is working the second time I try the same import but as you can see, it seems that "plot" is not recognized after all.

Thanks,
Mathieu