Midtrans Error

public class MainActivity extends AppCompatActivity {
    String client_key = "VT-client-ArZCkEXTCxexVsdY";
    String base_url = "http://kencana-dev.tiketlindo.com/";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

    SdkUIFlowBuilder.init(
            this,
            client_key,
            base_url,
            new TransactionFinishedCallback() {
                @Override
                public void onTransactionFinished(TransactionResult transactionResult) {
                    Toast.makeText(MainActivity.this, "transaction finished", Toast.LENGTH_SHORT).show();
                }
            }).buildSDK();

    Button btn_pay_now = (Button) findViewById(R.id.btn_pay_now);
    btn_pay_now.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            TransactionRequest transactionRequest = new TransactionRequest(String.valueOf(System.currentTimeMillis()), Double.parseDouble("80000"));

            ItemDetails item1 = new ItemDetails("19", 20000, 1, "mukena merah");
            ItemDetails item2 = new ItemDetails("13", 30000, 2, "baso galak");
            ArrayList<ItemDetails> itemDetailsArray = new ArrayList<>();
            itemDetailsArray.add(item1);
            itemDetailsArray.add(item2);
            transactionRequest.setItemDetails(itemDetailsArray);

            BillInfoModel billInfo = new BillInfoModel("bill key", "bill value");
            transactionRequest.setBillInfoModel(billInfo);

            CreditCard creditCardOption = new CreditCard();
            creditCardOption.setSaveCard(false);
            creditCardOption.setSecure(false);
            creditCardOption.setBank(BankType.BCA);
            creditCardOption.setChannel(CreditCard.MIGS);
            transactionRequest.setCreditCard(creditCardOption);
            transactionRequest.setCardPaymentInfo(getResources().getString(R.string.card_click_type_none), false);

            MidtransSDK.getInstance().setTransactionRequest(transactionRequest);
            MidtransSDK.getInstance().startPaymentUiFlow(MainActivity.this, PaymentMethod.BANK_TRANSFER);
        }
    });


    }
}