calling python interpreter

[Kranio]

Under Red Hat 5.x I use to call the file pippo.py as

$ python pippo.py

I would like to call it as

$ ./pippo.py 

by writing the first line

#!/usr/bin/python

but it gave me "access denied" message. The interperter is in the
right dir and I am the owner of the file; tha same happens being root.
What is the problem?

Marco Buzzo