Basic Listbox Adding

[Jester]

Hey all,

Got an easy one, well, what I would normally been ok with but must've been working too hard - I can't see why I'm having this problem.

Just trying to add items to a multiple select listbox:

<SELECT Name="servTimeRange" multiple="multiple">
	<?php showTimeRange(); ?>
</SELECT>

<a href="#" onClick="addTimeRange(document.getElementById('servTimeFrom').value,document.getElementById('servTimeTo').value); return false;">Add</a>

function addTimeRange(from,to) {
	var tstampFrom;
	var tstampTo;
	arrFrom = from.split(":");
	arrTo = to.split(":");
	if (document.serviceAdd.servTimeFromM.options[document.serviceAdd.servTimeFromM.selectedIndex].text == "pm") { (arrFrom[0] += 12); }
	if (document.serviceAdd.servTimeToM.options[document.serviceAdd.servTimeToM.selectedIndex].text == "pm") { (arrTo[0] += 12); }
	tstampFrom = arrFrom[0]+':'+arrFrom[1]+':00';
	tstampTo = arrTo[0]+':'+arrTo[1]+':00';
	var opt = document.createElement("option");
	opt.text = from+document.serviceAdd.servTimeFromM.options[document.serviceAdd.servTimeFromM.selectedIndex].text+' - '+to+document.serviceAdd.servTimeToM.options[document.serviceAdd.servTimeToM.selectedIndex].text;
	opt.value= tstampFrom+' - '+tstampTo;
	document.getElementByID("servTimeRange").options.add(opt);
}

Problem is just on the last line of the last group of code here, giving me the "object does not support this property or method" message - and it looks right to me, so probably needs a fresh pair of eyes.

I've also noticed that on the line "arrFrom[0] += 12", that despite the value in this array is a number, it's concatenating it - what's the best way to convert that value to an integer?

Thanks all,
Jess.