Selenium webdriver 找不到元素，请按下面的代码

我无法在这里找到元素，这是我的代码和资源附件

我发现了异常，请帮我解决。我正在尝试拖放功能

   public static void main(String[] args) {
    System.setProperty("webdriver.chrome.driver", "G:\\TopsAssignment\\SampleJavaExample\\lib\\chromedriver.exe");
    WebDriver driver = new ChromeDriver();

    driver.get("https://jqueryui.com/draggable/");
    driver.manage().window().maximize();
    driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);

    WebDriverWait wait = new WebDriverWait(driver, 30);
    wait.until(ExpectedConditions.elementToBeClickable(By.cssSelector("#draggable")));


    WebElement dragElement = driver.findElement(By.cssSelector("#draggable"));

    Actions acs = new Actions(driver);

    Action act = acs.dragAndDropBy(dragElement, 200, 500).build();

    act.perform();

    driver.close();

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使用下面的代码可以很好地工作

    public static void main(String[] args) {
    System.setProperty("webdriver.chrome.driver", "G:\\TopsAssignment\\SampleJavaExample\\lib\\chromedriver.exe");
    WebDriver driver = new ChromeDriver();

    driver.get("https://jqueryui.com/droppable/");
    driver.manage().window().maximize();
    driver.manage().timeouts().implicitlyWait(20, TimeUnit.SECONDS);

    driver.switchTo().frame(0);


    WebElement dragElement = driver.findElement(By.cssSelector("#draggable"));
    WebElement dropable = driver.findElement(By.id("droppable"));

    Actions acs = new Actions(driver);

    Action act = acs.dragAndDrop(dragElement,dropable).build();

    act.perform();

    driver.close();



}