python requests 400 error -

hi using python requests module. code is:

import requests  payload = {'awsaccesskeyid':'akiajhsxaecvml4xjt7nvvlaq',       'action':'listorders',       'createdafter':'2015-05-31t18%3a30%3a00z',       'marketplaceid':'a21tjruun4kgv',       'sellerid':'a3azitedavc4slu02m7',       'signaturemethod':'hmacsha256',       'signatureversion':2,       'timestamp':'2015-06-03t10%3a13%3a48z',       'version':'2013-09-01'}  response = requests.post('https://mws.amazonservices.in/orders/2013-09-01', params=payload)  print response.status_code 

these fake credentials

i : 400
doing wring?

i found third party tool called temboo provides api sdks many websites , there skd amazon aws in python , when downloaded , checked code listorders.py found these code below makes clear it's expecting date in iso 8601 date format (i.e. 2012-01-01).

super(listordersinputset, self)._set_input('awssecretkeyid', value) def set_createdafter(self, value): """ set value of createdafter input choreo. ((optional, date) date used selecting orders created after (or at) specified time, in iso 8601 date format (i.e. 2012-01-01). defaults today's date if not provided.)