enable check boxes?

I've wrtien a script that disables check boxes

e.g. document.form1.elements[day1times].disabled = true;

But if can't re-enable them

I've tried document.form1.elements[day1times].disabled = false;
but isn't working..

Any ideas ?

 

<script>
	function setState(ob) {
		if ( ob[1].disabled == true ) {
			ob[1].disabled = false;
		} else {
			ob[1].disabled = true;
		}
	}
</script>
<form action="" method="post" name="fsadf">
	<input id="what" name="what[]" type="checkbox" disabled value="" />
	<input id="what" name="what[]" type="checkbox" disabled value="" />
	<input name="dsf" type="button" value="Submit" onclick="setState(what)" />
</form>

Code (markup):