Unable to execute JavaScript with HtmlUnitDriver

Question

The following code declares a HtmlUnitDriver with javascript enabled using new HtmlUnitDriver(true) and then creates a JavaScriptExecutor like below

     WebDriver driver = new HtmlUnitDriver(true);
     JavascriptExecutor js = (JavascriptExecutor) ((HtmlUnitDriver)driver);

I find the html tag on which I have to add an attribute

      String xpathSrc = "//*[@id='formId']/table/tbody/tr/td/table/tbody/tr[2]/td[2]/table/tbody/tr/td/table/tbody/tr[4]/td[2]/input[2]";
    String xpathDest = "//*[@id='formId']/table/tbody/tr/td/table/tbody/tr[2]/td[2]/table/tbody/tr/td/table/tbody/tr[8]/td[2]/input[2]";

    WebElement elemSrc =  driver.findElement(By.xpath(xpathSrc));
    setAttributeValue(elemSrc, "value", src.toUpperCase());

    WebElement elemDest = driver.findElement(By.xpath(xpathDest));
    setAttributeValue(elemDest, "value", dest.toUpperCase());

then I call the following function

     public void setAttributeValue(WebElement elem, String attr, String value){
    String scriptSetAttrValue = "arguments[0].setAttribute(arguments[1],arguments[2]);";        
    js.executeScript(scriptSetAttrValue, elem, attr, value);
}

But after all my efforts I am unable to execute the code with HtmlUnitDriver but the same code runs efficiently with FirefoxDriver or PhantomJsDriver. I am inclined to use HtmlUnitDriver because of its speed but nothing seems to work.