Unable to get Comments data via API call

Unable to get Comments data via API call

I am currently implement system to retrieve ticket and its comment from Zoho Desk to Data warehouse using python.

I was able to get Tickets but comments data for each tickets is empty but on the Dashboard, there are couples of conversations logged.

We are running 
Zoho Desk : Free Edition
Zoho CRM : Free Edition

MY API Url is 
"https://desk.zoho.com/api/v1/tickets/{ticketID}/comments?include=mentions