Is it possible to update accountId in Zoho support ticket??

I wrote below code -
    mp = Map();
    mp.put("accountId",accountId);
    tkt_upd = zoho.support.updateRecord("Requests",portal,"Product Executives",tkt_id,mp);
    info tkt_upd;

and is showing output as - {"Status":"Record(s) updated successfully","Time":"2017-09-19 09:34:59"}

but when i check the response from API - https://desk.zoho.com/api/v1/tickets/<Ticket_Id> then, there is no change in the Account Id.