Creating new task API giving input parameter missing

Creating new task API giving input parameter missing

I am using ZOHO Portal API to create new Task. The documentation says only Name is required. However i have tried to send everything via APi but still i am getting input parameter missing.

Here are the fields I am sending via POST along with the url 

{
    "fields": {
        "name": "a",
        "person_responsible": 723522223,
        "tasklist_id": "1476105000001984003",
        "end_date": "11-13-20",
        "start_date": "11-06-20",
        "start_time": "01:00 pm",
        "end_time": "03:00 pm",
        "duration": 10,
        "duration_type": "days",
        "priority": "Low",
        "description": "b",
        "work_type": "work_hrs_per_day",
        "rate_her_hour": 10,
        "owner_work": "{\"user_id\":723522223,\"working_hours\":2}"
    },
    "url": "https://projectsapi.zoho.com/restapi/portal/xxxxxx/projects/xxxxxxx/tasks/",
    "response": "{\"error\":{\"code\":6831,\"message\":\"Input Parameter Missing\"}}\n"
}

What am I missing?