Error en el registro de la función FTX IO Futures_OP 4: 405: 405 No permitido

El código

def short(direction,price,amount):
    exchange.SetDirection('sell')
    logtype = LOG_TYPE_SELL
    para = ""
    para += "market='"+exchange.GetCurrency().replace('_USD', '-PERP') + "'"
    para += "&side='"+ direction + "'"
    para += "&price=" + str(price)
    para += "&type='" + "'limit'" + "'"
    para += "&size=" + str(amount)
    if direction == "'buy'":
        para += "&reduceOnly=true"
        logtype = LOG_TYPE_BUY
        exchange.SetDirection('closesell')
    para+="&postOnly=true"
    # para+="&timestamp="+ str(int(UnixNano() / 1000000))
    ret = exchange.IO("api", "POST", '/orders', para)
    exchange.Log(logtype, price, amount)
    return ret

Dirección del discohttps://www.fmz.com/robot/407656