logging module question

[s99999999s2003 at yahoo.com]

hi
i have defined a function
def logger(logfile,msg):
        import logging

        logging.basicConfig(level=logging.DEBUG,
                                   format='%(asctime)s %(levelname)-8s
%(message)s',
                                    datefmt='%a, %d %b %Y %H:%M:%S',
                                    filename='%s' % (logfile),
                                    filemode='a')
        logging.critical(msg)
        logging.error(msg)
        logging.warning(msg)
        logging.info(msg)
        logging.shutdown()

In my main code:

----- some python code here---
logger("test.log","error")
.....
.....
logger("test.log","another error")
...
logger("test.log","yet another error")
...
sys.exit(0)

When i do the above, i get :
self.stream.write(fs % msg)
ValueError: I/O operation on closed file

If i removed logging.shutdown(), it workds..what is wrong with my
function ? 
thanks