FIELD_IN_CRITERIA_NOT_AVAILABLE - BULK READ API PYTHON

FIELD_IN_CRITERIA_NOT_AVAILABLE - BULK READ API PYTHON

Hi, 

I'm trying to test the Bulk Read API using python by using the python native code that are available on:
https://www.zoho.com/crm/developer/docs/api/v2/bulk-read/create-job.html

I do have access to bulk.all but I'm havig this mensagem after trying to run the code:

HTTP Status Code : 400
{'status': 'error', 'code': 'FIELD_IN_CRITERIA_NOT_AVAILABLE', 'message': 'Field api name "Lead_Source" is not available for criteria [api_name=Lead_Source, comparator=equal, value=Advertisement]. Check visibility and permission for the field', 'details': {'field': {'id': '43xxxxxxxxxxxxxxxxx', 'api_name': 'Lead_Source', 'module': 'Contacts'}, 'api_name': 'Lead_Source', 'comparator': 'equal', 'value': 'Advertisement'}}

I didn't find why it's happing, could someone help me with that, please?