It looks like it is set up correctly. Are you sure the values for Legnth, Width, and Height values are set correctly in the cart? I see there is a typo in the word Length... that is fine as long is it is set that way.
Maybe try dumping the session on a blank page after the shipping is calculated and see if the values appear to be set correctly there:
<?php
@session_start();
var_dump($_SESSION);
?>