Check out this piece of code :
<select name="backgroundcolor" onchange="backgroundColor();">
<option value="200">Red</option>
....
</select>
I attempted the following code to choose the "Red" option but it didn't work.
Select dropDown = new Select(driver.findElement(By.name("backgroundcolor")));
dropDown.selectByValue("200");
I encountered a NoSuchElementException
Exception
Unable to locate element //*[name='backgroundcolor']