selenium.getDriver().findElement(By.id("s2id_customFilter")).sendKeys(Keys.ARROW_DOWN);

Am using the above code but it's not working."s2id_customFilter" is the id of the drop down.Am clicking on the id and sending keys but there's no action from selenium.

My code:

jQueryWebElement filterElement = selenium.jQuery("#s2id_customFilter");
selenium.jQuery(".select2-choice",filterElement).click();
JOptionPane.showMessageDialog(null, "one");
selenium.getDriver().findElement(By.id("s2id_customFilter")).sendKeys(Keys.ARROW‌​_DOWN);