fork problem

[DelPiccolo Ivano]

I have the following error when i try to fork :

Traceback (most recent call last):
  File "explorer_proxy.py", line 33, in ?
    child = os.fork()
AttributeError: 'module' object has no attribute 'fork'

Here is my code :
child = os.fork()
 if child == 0 :
        print "\nEntering in child process"

Where is my error ?????

Thanks