[SOLVED] Compare Additional Date

[SOLVED] Compare Additional Date

I wrote this script on Rule incident template
I want compare 2 additional date filed
=========
var x=$CS.getValue("GUDF_DATE1");
var y=$CS.getValue("GUDF_DATE2");
if (x<y) 
{
  alert("start date should granter end date"); 
}
======== 
it's not works