let mut hash_cache = sighash::SighashCache::new(&txclone);
    for (index, input) in transaction.input.iter_mut().enumerate() {
        let value = get_value(input, own_utxos);    // Look up the value by finding the corresponding UTXO
        let sighash = hash_cache
            .segwit_signature_hash(index, &own_address.script_pubkey(), value, SIG_HASH_TYPE)
            .expect("Creating the segwit signature hash failed.");

fn sign_transaction<SignFun>(
    own_public_key: &[u8],
    own_address: &Address,
    own_utxos: &[Utxo],
    mut transaction: Transaction,
    key_name: String,
    derivation_path: Vec<Vec<u8>>,
    signer: SignFun,
) -> Transaction
where
    SignFun: Fn(String, Vec<Vec<u8>>, Vec<u8>) -> Fut,
{

    let txclone = transaction.clone();
    let mut hash_cache = sighash::SighashCache::new(&txclone);
    for (index, input) in transaction.input.iter_mut().enumerate() {
        let value = get_value(input, own_utxos);    // Look up the value by finding the corresponding UTXO
        let sighash = hash_cache
            .segwit_signature_hash(index, &own_address.script_pubkey(), value, SIG_HASH_TYPE)
            .expect("Creating the segwit signature hash failed.");

        let signature = signer(key_name.clone(), derivation_path.clone(), sighash.to_vec()).await;

        // Convert signature to DER.
        let der_signature = sec1_to_der(signature);

        let mut sig_with_hashtype = der_signature;
        sig_with_hashtype.push(SIG_HASH_TYPE.to_u32() as u8);
        let witness_bytes = vec![sig_with_hashtype, own_public_key.to_vec()];
        input.witness = Witness::from_vec(witness_bytes);
    }

    transaction
}

010000000001016e97eae878274b6663923994bf7622c72ed41ce71d9d5d4091905378eeb0e5fa0000000000ffffffff0200e1f505000000001976a9148f7918f50cfd908ff82294a12c926f0fc52b0d1d88ac3e160d8f000000001600148be949ae15ee4b5da9af0ce2bf8d3f3c43c582da02483045022100999dd2a10b036d6b599d7d6b205f62b4dd14aca4b4c0d12224c0daa35c34bbea022025702dd922f94bd5b9444f798ab4ad7bcdbdd53568d7a45c6086a3e6f81b20d4012103366e75877b80252ff39e76229fe6d88d14e1150256bfdd27e7726b6b2cb23c0200000000

error code: -26
error message:
non-mandatory-script-verify-flag (Signature must be zero for failed CHECK(MULTI)SIG operation)

...
let sighash = txclone.signature_hash(index, &own_address.script_pubkey(), SIG_HASH_TYPE.to_u32());

let signature = signer(key_name.clone(), derivation_path.clone(), sighash.to_vec()).await;

// Convert signature to DER.
let der_signature = sec1_to_der(signature);

let mut sig_with_hashtype = der_signature;
sig_with_hashtype.push(SIG_HASH_TYPE.to_u32() as u8);
input.script_sig = Builder::new()
    .push_slice(sig_with_hashtype.as_slice())
    .push_slice(own_public_key)
     .into_script();
input.witness.clear();