daveVk - 1:04 am on Aug 30, 2012 (gmt 0)

No clue, try hard coding a value to firstHeight, to narrow problem done.

<script type="text/javascript">
function setSize(){
var firstLi = $('#hotelSlider').show().find('li:first-child'),
var firstHeight = firstLi.css('height'),
var container= $('#hotelSlider');
firstHeight = '500px';
container.css({
'height': firstHeight
});
}
</script>

or use alert on firstHeight