[newbie] problem with module PyVisa

[Jean Dubois]

I'm trying to control a programmable power supply via USB using
python.
After doing some googling I thought I should use PyVisa for this
purpose, so I installed it as follows:
tar xvfz PyVISA-1.4.tar.gz
cd PyVISA-1.4
python setup.py install

Installation seems to finish without errors.

When I start a python session things go wrong as you can see in the
output below,
can anyone here tell me how to proceed correctly? thanks in advance.

>>> import visa
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
visa.py", line 1, in <module>
    from pyvisa.visa import *
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/visa.py", line 231, in <module>
    resource_manager = ResourceManager()
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/vpp43.py", line 105, in __new__
    it.init(*args, **kwds)
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/visa.py", line 227, in init
    self.session = self.vi = vpp43.open_default_resource_manager()
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/vpp43.py", line 758, in open_default_resource_manager
    visa_library().viOpenDefaultRM(byref(session))
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/vpp43.py", line 175, in __call__
    self.load_library()
  File "/usr/local/lib/python2.6/dist-packages/PyVISA-1.4-py2.6.egg/
pyvisa/vpp43.py", line 146, in load_library
    self.__lib = self.__cdecl_lib = cdll.LoadLibrary(path)
  File "/usr/lib/python2.6/ctypes/__init__.py", line 431, in
LoadLibrary
    return self._dlltype(name)
  File "/usr/lib/python2.6/ctypes/__init__.py", line 353, in __init__
    self._handle = _dlopen(self._name, mode)
OSError: /usr/local/vxipnp/linux/bin/libvisa.so.7: cannot open shared
object file: No such file or directory