OK, I tested the form, and got the following error:
Notice: Undefined index: NDallas in /var/www/vhosts/nerdyrat.com/httpdocs/form.php on line 13
Notice: Undefined index: SDallas in /var/www/vhosts/nerdyrat.com/httpdocs/form.php on line 14
Warning: Cannot modify header information - headers already sent by (output started at /var/www/vhosts/nerdyrat.com/httpdocs/form.php:13) in /var/www/vhosts/nerdyrat.com/httpdocs/form.php on line 28
this is because i didn't check either the NDallas or SDalas check boxes
when setting the session, you should use isset() to see if the form elements are set or not:
for example:
$_SESSION['NDallas']=isset($_POST['NDallas'])?$_POST['NDallas']:"";
i then when to the results page, and saw the information I had entered was displayed meaning the sessions are being set.
the vardump code at the bottom of the page should be:
<?php var_dump($_SESSION); ?>
but it seams to be working in my test.