触发事件后，metamask 提示，转账不能成功，但在remix和etherscan均能正常执行。请问如何解决？

This transaction is expected to fail. Trying to execute it is expected to be expensive but fail, and is not recommended.

React代码

async function payWithMetamask() {

let ethereum = window.ethereum;
// Request account access if needed
await ethereum.enable();
let provider = new ethers.providers.Web3Provider(ethereum);    

// Acccounts now exposed
const tx = [{
    from: walletAddress,
    to: contractAddress,
    value: ethers.utils.parseUnits('1000000', 'gwei').toHexString(),
}];

const transactionHash = await provider.send('eth_sendTransaction', tx)
console.log('transactionHash is ' + transactionHash);

}

合约代码

function buy() public payable{
        uint256 amount = msg.value;
        address buyer = msg.sender;
        require(amount > 1000, 'money not enjoy.'); 
        acl.push(buyer);
    }