Dynamic Dropdown list in Adobe Acrobat Pro XI

Ok guys and gals.  I'm going nuts here. I have been doing a lot of research on a dynamic drop down list for adobe acrobat pro XI.  I've seen a few things but nothing is working.  Here is what I am trying to do.  I have two drop down boxes in a form titled "Status" and "Rank."  I want Status to have two labels to chose from; NCO and OFFICER.  In the "Rank" field I want the list of either all of the NCO or Officer ranks to appear for selection based upon which option is chosen in the field "Status."  I tried this script which has gotten me the closest but only displays the data in the "Rank" field for NCO when NCO is the first item in the list in the "Status" field and the data that does appear in the "Rank" field does not display as drop down options.  Rather, it displays as a line of text with commas.  If I chose the Officer item as the 2nd item in the list, I get no change in the "Rank" field.  It stays populated with the original NCO data.   grrrrrr.  This script may be too simple and not what I need but it functioned closer than anything else I found.  Here is what that script looks like:

switch (event.value)  {

    case "NCO":

         this.getField("Rank").setItems("PV1,PV2");

         break;

    case "Officer"

         this.getField("Rank").setItems("2LT, 1LT");

         break;

}