Python Requests Throwing Cookie Error

I am trying to post popup form data to a local website. To do this, I emulate the information of the request headers and the data and cookies provided by the site. (Note: I'm pretty much editing my email and password from code (for obvious reasons), but all other codes will remain the same.)

I've tried bulkheading cookies, headers, requests, data, etc. Also, I checked the cookie and the expected headers and data in the network inspector. I can easily set a cookie using the requests request code . I cannot explain why my code will not work on a real site and I would be very grateful for any help. See the following code for more information.

import requests
import robobrowser
import json

br = robobrowser.RoboBrowser(user_agent="Windows Chrome",history=True)

url = "http://posting.cityweekly.net/gyrobase/API/Login/CookieV2"
data ={"passwordChallengeResponse":"....._SYGwbDLkSyU5gYKGg",
        "email": "<email>%40bu.edu",
        "ttl":"129600",
        "sessionOnly": "1"
        }
headers = {
    "Origin": "http://posting.cityweekly.net",
    "Accept-Encoding": "gzip, deflate",
    "Accept-Language": "en-US,en;q=0.8,ru;q=0.6",
    "User-Agent": "Windows Chrome", #"Mozilla/5.0 (Windows NT 6.3; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.65 Safari/537.36",
    "Content-Type": "application/x-www-form-urlencoded; charset=UTF-8",
    'Accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8',
    "Referer": "http://posting.cityweekly.net/utah/Events/AddEvent",
    "X-Requested-With": "XMLHttpRequest",
    "Connection": "keep-alive",
    "Cache-Control": "max-age=0",
    "Host":"posting.cityweekly.net"

}
cookie = {"Cookie": "__utma=25975215.1299783561.1416894918.1416894918.1416897574.2; __utmc=25975215; __utmz=25975215.1416894918.1.1.utmcsr=(direct)|utmccn=(direct)|utmcmd=(none); __qca=P0-2083194243-1416894918675; __gads=ID=e3b24038c9228b00:T=1416894918:S=ALNI_MY7ewizuxK0oISnqPJWlLDAeKFMmw; _cb_ls=1; _chartbeat2=D6vh2H_ZbNJDycc-t.1416894962025.1416897589974.1; __utmb=25975215.3.10.1416897574; __utmt=1"}
r = br.session.get(url, data=json.dumps(data), cookies=cookie, headers=headers)
print r.headers
print [item for item in r.cookies.__dict__.items()]

      

        
        
        
      

    

Note that I am printing a cookie and that the cookie (dictionary) attribute is empty.