Invalid Ticket error

Invalid Ticket error

unable to fetch leads using API, it errors out as "Invalid ticket" error code "4834"

https://crm.zoho.com/crm/private/xml/Leads/getRecords?authtoken=e836dc5d3c8a0905d75e3e399257fe84&scope=crmapi&selectColumns=Leads(First%20Name,Last%20Name,Email,Company,Campaign%20Source)&version=1

the python client
=============
import urllib
import urllib2
module_name = 'Leads'
authtoken = 'e836dc5d3c8a0905d75e3e399257fe84'
params = {'authtoken':authtoken,'scope':'crmapi'}
data = urllib.urlencode(params)
request = urllib2.Request(final_URL,data)
response = urllib2.urlopen(request)
xml_response = response.read()
print xml_response

NOTE: I see the Auth ID is valid when I see from my " Active Authtokens"