Selenium webdriver 无法通过Katalon Studio中的索引在下拉列表中选择值

我目前正在使用Katalon Studio自动化一个用例，其中包括下拉菜单上的操作

我确信我正确地编写了自动化代码，但由于某些原因，我发现我的代码没有按预期工作。在DropdownByIndex中选择选项的代码既不工作也不生成任何异常。但当我使用相同的代码在下拉列表中通过可见文本选择选项时，它似乎工作得很好

下面是我的代码。请仔细研究一下，并向我建议一些替代方案，通过索引对下拉菜单进行操作，从而自动化用例

String FeeTypeDropDownInAddFeeSidePanelXpath = "//select[@name='serviceLevelFee']"
String ServiceDropDownInAddFeeSidePanelXpath = "//select[@name='service']"

public void addFee(int FeeTypeIndex,int ServiceIndex)
    {   
        //the below works
        rbu.clickOnWebElement(AddFeeButtonXpath)
        WebUI.delay(5)

        println ("selecting Fee type from the respective drop down")
        selectAValueInDropdownByIndex(FeeTypeDropDownInAddFeeSidePanelXpath,FeeTypeIndex)
        WebUI.delay(5)

        println ("selecting Service from the respective drop down")
        selectAValueInDropdownByIndex(ServiceDropDownInAddFeeSidePanelXpath,ServiceIndex)
        WebUI.delay(5)

        // the below works
        rbu.clickOnWebElement(SaveButtonInAddFeeSidePanelXpath)
        WebUI.delay(5)
    }


public void selectAValueInDropdownByIndex(String xpath,int index)
    {
        //this method selects a option in drop down by its index
        //taking the elements xpath and index as parameters.also handels the StaleElementReferenceException which
        // is observed redundant thru RRm drop down web elements

        try{
            println ("inside try")
            String elementXpath = xpath
            WebElement webelement = driver.findElement(By.xpath(elementXpath))
            Select webelementSelect = new Select(webelement)
            webelementSelect.selectByIndex(index)
        }
        catch(StaleElementReferenceException e)
        {
            println ("inside catch of StaleElementReferenceException")
            String elementXpath = xpath
            WebElement webelement = driver.findElement(By.xpath(elementXpath))
            Select webelementSelect = new Select(webelement)
            webelementSelect.selectByIndex(index)
        }
        catch(NoSuchElementException e)
        {
            println("NoSuchElementException raised")
            while (true)
            {
                String elementXpath = xpath
                WebDriverWait wait = new WebDriverWait(driver,35)
                WebElement webelement = wait.until(ExpectedConditions.visibilityOfElementLocated(By.xpath(elementXpath)))
                Select webelementSelect = new Select(webelement)
                webelementSelect.selectByValue(index)
                if(!webelement.isDisplayed())
                {
                    break
                    //option selected in the drop down
                }
            }
        }
    }