Having issues with the Buy Contract API

Developers
1

Hi.
I am trying to use the Buy Contract API for an Accumulator Trade type. I am supplying this request

{
    "buy": "63e1aa93-9e99-e3fb-d36c-d76f47dbc412",
    "price": 1,
    "parameters": {
        "contract_type": "ACCU",
        "basis":"stake",
        "symbol": "R_100",
        "currency": "USD",
        "limit_order": {
            "take_profit": 1
        }
    }
}

And I am getting this response back

{
  "echo_req": {
    "buy": "63e1aa93-9e99-e3fb-d36c-d76f47dbc412",
    "parameters": {
      "app_markup_percentage": "0",
      "basis": "payout",
      "contract_type": "ACCU",
      "currency": "USD",
      "limit_order": {
        "take_profit": 1
      },
      "symbol": "R_100"
    },
    "price": 1,
    "req_id": 10
  },
  "error": {
    "code": "ContractCreationFailure",
    "message": "Please specify either payout or stake."
  },
  "msg_type": "buy",
  "req_id": 10
}

I have provided the basis as per the docs
What am I missing?
Any help is appreciated