ehters连接stark的合约,调用balanceOf方法报错balanceOf not a function

代码如下

const stkProvider = new ethers.JsonRpcProvider(`https://starknet-mainnet.infura.io/v3/${this.apiKey}`);
            const wallet = new ethers.Wallet(secret, stkProvider);
            const starkGateContract = new ethers.Contract(this.starkJson.starkGate.address, this.starkJson.starkGate.abi2, wallet);
            console.log(stkProvider)

            console.log(starkGateContract)
            const name = starkGateContract.balanceOf(addr);

报错如下图