Zoho CRM REST V2 Api returns "AUTHENTICATION_FAILURE" with no details

Hi All,

I am trying to log a call in Zoho crm using V2 Rest API's. I am able to exchange the refresh token and get a new access token, fetch the details of the call already saved within zoho crm etc. But whenever I send a POST request to https://www.zohoapis.com/crm/v2/Calls as explained in https://www.zoho.com/crm/help/api/v2/insert-records-examples.html#insert-calls

I always get the following error.

{"code":"AUTHENTICATION_FAILURE","details":{},"message":"Authentication failed","status":"error"}

I can do a GET request to ../crm/v2/Calls and get details of an already logged call fine using the same access token. I am sure that I am using the access token soon after it is generated and it is not expired which is causing the above issue.

Any help is highly appreciated.

Thanks,

Gopikrishnan V