Javascript DOM selecting HELP

[saucey]

I have this code placed below, can some explain were i am going wrong its not alerting me with any values when my form seletion gets processed.

function validateForm()
{
var e = document.getElementById("carsel");
var btn = e.options[selectedIndex].value;

if (btn == null) alert('No radio button selected');
else alert('Button value ' + btn + ' selected'); 
  return false;
  }