Changing a dropdown list value makes the value blank

Changing a dropdown list value makes the value blank

Hi,
I'm trying to change a dropdown value depending on a radio button that has been selected. My code didn't work so I brought it back to the absolut basics, which look like this:
  1. $(document).ready(function(){
  2. jQuery('#attribute92').val("W");
  3. });
My DD looks like this:
  1.                <select name="super_attribute[92]" id="attribute92" class="required-entry super-attribute-select">
  2.                   <option value="">D</option><option value="3" price="0">W</option><option value="10" price="0">VW</option></select>
It does contain the value "W", but what it looks like after the code is executed is:

As you can see, this should not even be an option. What am I doing wrong? I've tried multiple ways of selecting it...