urllib HTTP Error: 400 Bad Request

Question

I looked at this answer: Again urllib.error.HTTPError: HTTP Error 400: Bad Request because it was very similar to my question, but that solution did not work. I'm using Python 3.3.2. The lines that are like ..something.. are just values I replaced to protect my privacy. They should be strings

I'm getting an Error 400: Bad request from this code:

import urllib.parse
import urllib.request

url = '..url..'
user_agent = 'Mozilla/4.0 (compatible; MSIE 5.5; Windows NT)'
values = {'email':'..my email address..',
          'github':'..my github account..'}
headers = {'User-Agent':user_agent}
data = urllib.parse.urlencode(values)
data = data.encode('utf-8')
req = urllib.request.Request(url, data, headers)
response = urllib.request.urlopen(req) #this line causes the errors
page = response.read()

This is the particular error message:

Traceback (most recent call last):
  File "/Users/.../Documents/Code 2040/File.py", line 23, in <module>
    response = urllib.request.urlopen(req)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 156, in urlopen
    return opener.open(url, data, timeout)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 475, in open
    response = meth(req, response)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 587, in http_response
    'http', request, response, code, msg, hdrs)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 513, in error
    return self._call_chain(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 447, in _call_chain
    result = func(*args)
  File "/Library/Frameworks/Python.framework/Versions/3.3/lib/python3.3/urllib/request.py", line 595, in http_error_default
    raise HTTPError(req.full_url, code, msg, hdrs, fp)
urllib.error.HTTPError: HTTP Error 400: Bad Request