Volta Testnetwork中未进行交易的原因可能是什么？

Question

我正在使用Express框架编写Nodejs应用程序。我尝试将一个以太币从一个帐户发送到另一个帐户，即使我得到了交易哈希，该交易也没有通过。我已经读过汽油价格可能太低了，但是由于我将价格设置为5.000.000，所以它再次失效了。当我调用web3.eth.getTransactionReceipt('txHash')时，它返回null，因此我猜交易失败。

这是我的代码：

router.get('/', (req, res, next) => {
    // Build a transaction object
    web3.eth.getTransactionCount(ad2, (err, txCount) => {
        const txObject = {
            nonce: toHex(txCount),
            to: ad1,
            value: toHex(web3.utils.toWei('1', 'ether')),
            gasLimit: toHex(21000),
            gasPrice: toHex(web3.utils.toWei('12', 'gwei'))
        }

        // Sign the transaction
        const tx = new Tx(txObject);
        tx.sign(pk2);

        const serializedTx = tx.serialize();
        const raw = '0x' + serializedTx.toString('hex')

        // Broadchast the transaction to the network
        web3.eth.sendSignedTransaction(raw, (err, txHash) => {
            console.log('txHash:', txHash);

            web3.eth.getTransactionReceipt(txHash, (err, receipt) => {
                console.log('receipt: ', receipt);

                if (receipt == null) {
                    // Render the page
                    res.render('sendTransaction', {
                        receiptSuccess: 0,
                        blockHash: 'No Receipt Found'
                    });
                } else {
                    // Render the page
                    res.render('sendTransaction', {
                        receiptSuccess: 1,
                        blockHash: receipt.blockHash,
                        blockNumber: receipt.blockNumber,
                        transactionHash: receipt.transactionHash,
                        from: receipt.from,
                        to: receipt.to,
                        contractAddress: receipt.contractAddress,
                        gasUsed: receipt.gasUsed
                    });
                }
            });
        });
    });
});

我该怎么做才能成功地将交易从地址1发送到地址2？上面的代码缺少什么？

谢谢！