币安期货Invalid symbol

def main(): exchange.SetCurrency(“ETH_USDT”) exchange.SetContractType(“swap”) message =“symbol=” + “ETH_USDT” + “&side=BUY” + “&type=MARKET”+ “&quantity=0.01” id = exchange.IO("api", “POST”, “/fapi/v1/order”, message)

币安期货，无论我"ETH_USDT"怎么改，都会提示Futures_OP 4: 400: {“code”:-1121,“msg”:“Invalid symbol.”} 用系统提供的exchange.Buy(-1, 0.01)则可以下单到交易所。 错在哪里？