[jQuery] Counting Divs (IE6)

I am having a problem counting the number of divs inside a container,

var cellCount = $("#cellCont").children().length;

cellCount is coming up undefined in IE6. Any idea why?

here's the html:

<div class="block" id="cellCont">
<div class="cell" id="cellFirst"><?php include('design/print/
brochures.php'); ?></div>
<div class="cell"><?php include('design/print/catalog.php'); ?></
div>
<div class="cell"><?php include('design/print/annual_reports.php'); ?
></div>
<div class="cell"><?php include('design/print/magazines.php'); ?></
div>
<div class="cell"><?php include('design/print/direct_mail.php'); ?></
div>
<div class="cell"><?php include('design/print/newsletters.php'); ?></
div>
<div class="cell"><?php include('design/print/
product_services.php'); ?></div>
</div>