'NoneType' object is not subscriptable

MOIB1200

Dear Team,
I am using first time algo trading. During order placement i am getting below error,

Order placement failed: {} 'NoneType' object is not subscriptable

Input Parameter as follows,
orderparams = {
"variety": "NORMAL",
"tradingsymbol": "RVNL-EQ",
"symboltoken": "2246",
"transactiontype": "BUY",
"exchange": "NSE",
"ordertype": "MARKET",
"producttype": "INTRADAY",
"duration": "DAY",
"price": "76",
"squareoff": "0",
"stoploss": "0",
"quantity": qty
}

MOIB1200

@MOIB1200 Please qty as number instead of string.