python - Twython update_status_with_media error

Question

I have the following code:

photo = open(os.path.join("images", localFileName), 'rb')
tweetThis = "status"
twitter.update_status_with_media(status=tweetThis, media=photo)

Here is the traceback:

    twitter.update_status_with_media(status=status, media=photo)
  File "/usr/local/lib/python2.7/site-packages/twython/endpoints.py", line 107, in update_status_with_media
    return self.post('statuses/update_with_media', params=params)
  File "/usr/local/lib/python2.7/site-packages/twython/api.py", line 234, in post
    return self.request(endpoint, 'POST', params=params, version=version)
  File "/usr/local/lib/python2.7/site-packages/twython/api.py", line 224, in request
    content = self._request(url, method=method, params=params, api_call=url)
  File "/usr/local/lib/python2.7/site-packages/twython/api.py", line 194, in _request
    retry_after=response.headers.get('retry-after'))
twython.exceptions.TwythonError: Twitter API returned a 403 (Forbidden), Status creation failed: Tweet creation failed.

I have tested twitter.update_status(status='TEST') which works correctly meaning I have the correct credentials and permissions. What's wrong with the media version?