PHP session variable not maintained after form submit

Question

First off, I am new here and I don't know how to format my post nicely. Apologies.
My script starts with

<?php 
 if (!isset($_SESSION)) {
 session_start();
 }
 ini_set('soap.wsdl_cache_dir', "/tmp/");
?>

The form posts onto itself

form action = \"index.php\" method = \"POST\"

While debugging I noticed that after every postback, the session id changes and I understand that it should't. There are no session_destroy() calls or other session_start() function calls in the script. I'm unsure what additional information you need but I'm sure you'll let me know. Thanks in advance!

EDIT Here is the session section of the php_info()

Answer 1

try changing this:

if (!isset($_SESSION)) {
 session_start();
 }

into this:

 session_start();