What is the Desk API?

What is the Desk API?

I'm trying to fetch a lookup field data from desk to our creator application and it doesn't work.
I'm guessing that my search parameter is wrong?

On my trial function fetch if I use these:
tickets = invokeurl
[
type :GET
headers:{"featureFlags":"lookUp"}
connection:"deskconnect"
];
I can get the result in json:
customFields": {
"Bill To": {
      "accountName": "xxxxxxxxxxx",
      "id": "351081000013982683"
    },
or
cf": {
"cf_client": {
      "accountName": "xxxxxxxxxx",
      "id": "351081000013982683"
    },

however, on my workflow
zoho.desk.searchRecords("orgID","Tickets",searchValue,0,5,"deskconnect");
for each  Ticket_Rec in PM_TicketRecord.get("data")
{
if(Ticket_Rec.get("departmentId") == "deptID" && Ticket_Rec.get("category") == "Scheduled Maintenance")
    {
            input.Bill_To = Ticket_Rec.get("customFields").get("Bill To").get("accountName");  -always an error
   }
}

Any idea on this?