我正在flutter上开发一个dapp（去中心化应用程序），这是一个基本的应用程序，具有基本的智能合约和函数，我创建了一个getbalance方法和submit方法，分别在交易时获取余额、取款和存款函数。callcontract部分我添加了fetchidfromnetwork，我收到了此错误
错误：

E/flutter (30816): [ERROR:flutter/lib/ui/ui_dart_state.cc(198)] Unhandled Exception: Invalid argument(s): You can't specify loadChainIdFromNetwork and specify a custom chain id!
E/flutter (30816): #0      _fillMissingData (package:web3dart/src/core/transaction_signer.dart:20:5)
E/flutter (30816): #1      Web3Client.signTransaction (package:web3dart/src/core/client.dart:316:32)
E/flutter (30816): #2      Web3Client.sendTransaction (package:web3dart/src/core/client.dart:285:24)
E/flutter (30816): #3      _MyHomePageState.Submit (package:mad_froggys/main.dart:133:36)
E/flutter (30816): <asynchronous suspension>
E/flutter (30816): #4      _MyHomePageState.Sendcoin (package:mad_froggys/main.dart:142:20)
E/flutter (30816): <asynchronous suspension>
E/flutter (30816):

这是我代码：main.dart

import 'dart:ffi';

import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:http/http.dart';
import 'package:mad_froggys/slider.dart';
import 'package:velocity_x/velocity_x.dart';
import 'package:web3dart/web3dart.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      debugShowCheckedModeBanner: false,
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Mad froggys'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {

  late Client httpClient;
  late Web3Client ethClient;
  bool data = false;
  int myAmount = 1;

  final myAdress = "0x0FD0F0ED218D5D91C9fB702E53c2FA1C65bCF805";

  var myData;

  @override
  void initState() {
    httpClient = Client();
    ethClient = Web3Client("https://rinkeby.infura.io/v3/ff6f20460b7543dea923f0b9f987b2ac", httpClient);
    super.initState();

    getBalance(myAdress);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Vx.gray300,
      body:ZStack([
        VxBox()
            .green600
            .size(context.screenWidth,context.percentHeight*30)
            .make(),
        VStack([
          (context.percentHeight*10).heightBox,
          "\$Madfroggys".text.xl4.white.center.bold.makeCentered().py16(),
          (context.percentHeight*5).heightBox,
          VxBox(child: VStack([
            "Balance".text.gray500.bold.xl2.makeCentered(),
            10.heightBox,
            data?"\$$myData".text.bold.green600.xl4.makeCentered().shimmer():CircularProgressIndicator().centered(),

          ]).py16())
              .white
              .size(context.screenWidth,context.percentHeight*15)
              .rounded
              .shadowXl
              .make()
              .p16(),
          30.heightBox,
          SliderWidget(min: 0,max: 100,finalvalue: (value){
            myAmount = (value*100).round();
            print(myAmount);
          },).centered(),
          HStack([
            FlatButton.icon(
                onPressed:()=>getBalance(myAdress), icon:Icon(Icons.refresh,color: Colors.white,),
                color: Colors.cyan,
                shape: Vx.roundedSm,
                label: "refresh".text.white.make()),
            FlatButton.icon(
                onPressed:()=>Sendcoin(), icon:Icon(Icons.refresh,color: Colors.white,),
                color: Colors.cyan,
                shape: Vx.roundedSm,
                label: "deposit".text.white.make()),
            FlatButton.icon(
                onPressed:()=>Withdrawcoin(), icon:Icon(Icons.refresh,color: Colors.white,),
                color: Colors.cyan,
                shape: Vx.roundedSm,
                label: "withdraw".text.white.make())
          ],alignment: MainAxisAlignment.spaceAround,axisSize: MainAxisSize.max,
          ).p16()
        ]),
      ])

    );
  }

  //for reading the balance

  Future<void> getBalance(String targetAdress) async {
  //  EthereumAddress adress = EthereumAddress.fromHex(targetAdress);
    List<dynamic> result = await query("getBalance",[]);//will give the function and argument to query

    myData = result[0];
    data = true;
    setState(() {

    });
  }

  // submit metheod
  Future<String>Submit(String functionName,List<dynamic> args) async{
    EthPrivateKey credentials = EthPrivateKey.fromHex("84a6fa216233a59b01c4a35acdf1501f0797130acf23f81420432d67d8805f59");
    DeployedContract contract = await loadContract();
    final ethFunction = contract.function(functionName);

    **final result = await ethClient.sendTransaction(credentials,
        Transaction.callContract(contract: contract, function:ethFunction,
            parameters:args),fetchChainIdFromNetworkId: true);**

    return result;
  }
// writing and sending balance
  Future<String>Sendcoin() async{
    var bigAmount = BigInt.from(myAmount);
    var response = await Submit("withdrawBalance",[bigAmount]);
    print("sended");

    return response;
  }
//writing and withdraw balance
  Future<String>Withdrawcoin() async{
    var bigAmount = BigInt.from(myAmount);
    var response = await Submit("depositBalance",[bigAmount]);
    print("withdrawn");

    return response;
  }

  Future<DeployedContract>loadContract()async{
    String abi = await rootBundle.loadString("assets/abi.json");
    String contractAdress = "0xBed4D1f72eFB636CEc6Dea03f3522D0db51d556d";

    final contract = DeployedContract(ContractAbi.fromJson(abi,"MADfroggys"),EthereumAddress.fromHex(contractAdress));
    return contract;
  }

  Future<List<dynamic>>query(String functionName,List<dynamic>args) async{
    final contract = await loadContract(); // we have to load the contract
    final ethFunction = contract.function(functionName); // function name is given as argument
    final result = await ethClient.call(contract:contract, function:ethFunction, params:args);

    return result;
  }
}

我不知道该怎么办