There are two things going on here. First is do you want the “dummy” value to show up in the list of values (LOV) or not. If not, you don’t need to do the union from dual stuff. Second is you need to handle the dummy value in the condition object. The code to do that is covered quite well in the Designer FAQ here. The FAQ is for a character object and uses the word “All”. In order to make this work with a numeric value, you have to use a numeric substitute for the word “ALL” which you have done with the part number 9999.
Dave Rathbun 
(BOB member since 2002-06-06)