Xcode UI测试找不到passwordTextField

我在Xcode中编写一个简单的UI测试,遇到了一些问题。我有usernameTextField和passwordTextField。我无法引用passwordTextField。这是我的测试和错误。

func test_should_create_an_account_and_take_them_to_confirmation_screen() {

        let usernameTextField = self.app.textFields["usernameTextField"]
        usernameTextField.tap()
        usernameTextField.typeText("johndoe")

        let passwordTextField = self.app.textFields["passwordTextField"]
        passwordTextField.tap()
        passwordTextField.typeText("password123")

        self.app.buttons["registerButton"].tap()

        XCTAssertEqual(self.app.navigationBars.element.identifier, "BankAccount.LoginViewController")

    }