Mod_python error: "PythonHandler mod_python.psp"

Traceback (most recent call last):

  File "/usr/lib/python2.4/site-packages/mod_python/apache.py", line 299, in HandlerDispatch
    result = object(req)

  File "/usr/lib/python2.4/site-packages/mod_python/psp.py", line 301, in handler
    p = PSP(req)

  File "/usr/lib/python2.4/site-packages/mod_python/psp.py", line 111, in __init__
    self.load_from_file()

  File "/usr/lib/python2.4/site-packages/mod_python/psp.py", line 164, in load_from_file
    raise ValueError, "%s is not a file" % filename

ValueError: /var/www/html/reddot/formulare/recherche.psp is not a file