Why my HtmlUnit Login function does not work

Question

I am trying to submit my account info into this page (https://yoyaku.sports.metro.tokyo.lg.jp/user/view/user/homeIndex.html?te-uniquekey=1887c057141). But for some reason, when I use click method in navigateToOldVotePage function in below, it shows me username and password is empty error. I cannot figure out why the entered information is not submitted...

public static HtmlPage loginToVotePage(WebClient webClient, Account account) {
        HtmlPage loginPage = navigateToLoginPage(webClient);
        HtmlPage loginPage = navigateToOldLoginPage(webClient);
        return navigateToOldVotePage(loginPage, account);
    }

    private static HtmlPage navigateToOldLoginPage(WebClient webClient) {
        try {
            HtmlPage page = webClient.getPage(OLD_HOME_URL);
            final List<FrameWindow> window = page.getFrames();
            final HtmlPage pageTwo = (HtmlPage) window.get(1).getEnclosedPage();
            HtmlAnchor loginAnchor = pageTwo.getFirstByXPath(OLD_LOGIN_XPATH);
            return loginAnchor.click();

        } catch (Exception e) {
            System.err.println("Error happend duing navigating to login page: " + e);
        }

        return null;
    }

    private static HtmlPage navigateToOldVotePage(HtmlPage page, Account account) {
        try {
            HtmlInput userInput = page.getElementByName("userId");
            HtmlInput pwdInput = page.getElementByName("password");
            userInput.setValueAttribute(account.toeiId);
            pwdInput.setValueAttribute(account.password);
            
            HtmlAnchor submitLogin = page.getFirstByXPath("//*[@id='disp']/center/form/table[5]/tbody/tr[1]/td[2]/table/tbody/tr[2]/td/a");
            HtmlPage loggedIn = submitLogin.click();

            // 168...: /web/rsvWUA_Action.do

            System.out.println(loggedIn.asXml());

        } catch (Exception e) {
            System.err.println("Error happend duing loging process: " + e);
        }

        return null;
    }