Unable to process your request. Please verify if the name and value is appropriate

Unable to process your request. Please verify if the name and value is appropriate

Error message when I tried to access CRM api Error is following :

Unable to process your request. Please verify if the name and value is appropriate for the "authtoken" parameter.

I have tried with two authtokens also but every time same error is showing.

Code for python is:

import urllib

import urllib2

module_name = 'Leads'

authtoken = '4406d0a010e244503c005f8191a6XXXX'

params = {'authtoken':authtoken,'scope':'crmapi'}

final_URL = "https://crm.zoho.com/crm/private/xml/"+module_name+"/getRecords"

data = urllib.urlencode(params)

request = urllib2.Request(final_URL,data)

response = urllib2.urlopen(request)

xml_response = response.read()

print xml_response