Why doesn't my Python Selenium test work?

Question

Whenever I try to run a Python test with Selenium RC, it doesn't work. Here's the output I get when I try to run test_default_server.py:

$ python test_default_server.py
Using selenium server at localhost:4444
E
======================================================================
ERROR: testLinks (__main__.TestDefaultServer)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test_default_server.py", line 32, in setUp
    self.selenium.start()
  File "/home/jason/projects/test/web/selenium-rc/selenium-python-client-driver-1.0.1/selenium.py", line 189, in start
    result = self.get_string("getNewBrowserSession", [self.browserStartCommand, self.browserURL, self.extensionJs])
  File "/home/jason/projects/test/web/selenium-rc/selenium-python-client-driver-1.0.1/selenium.py", line 219, in get_string
    result = self.do_command(verb, args)
  File "/home/jason/projects/test/web/selenium-rc/selenium-python-client-driver-1.0.1/selenium.py", line 215, in do_command
    raise Exception, data
Exception

----------------------------------------------------------------------
Ran 1 test in 0.004s

FAILED (errors=1)

Does anyone know why this could be happening?

Thanks, Jason