how do I get trc20 network address for subaccount

I try /sapi/v1/capital/deposit/subAddress with parameters
email=customervirtualemailaddress,
coin=USDT,
network=TRC20

response message is -9000:“The deposit has been closed”

Use /sapi/v1/capital/config/getall to know networks, in this case the network is “TRX”