脚本不会获得会话变量

I made a website using WordPress, and on one page I've included my own script to guide users through a series of steps to calculate an outcome. The scripts are included in this order

Main page -> includes my Wizard.php -> Wizard.php include's Wizard_Step_xx.php

The Wizard reload's new steps every time from Step_01 until Step_10.php, this is done by a jQuery script.

Now my problem is that whenever a user finishis this "Wizard" he gets the option to log in and get redirected to his own page. Now when a user clicks the link to get to the "Wizard" I want to show the users personal page instead of showing him the first step of the wizard which would normally happen.

I've made this simple script that sets a $_SESSION variable when the user logs in :

//Validate Log In
if(isset($_POST['Validate'])) //submit login button
{
   $inlog_naam = ( $_POST['inlognaam'] );
   $wachtwoord = ( $_POST['wachtwoord'] );

   $try        = mysql_query("SELECT * FROM xxxx WHERE username = '$inlog_naam' AND password = '$wachtwoord'") or die (mysql_error() );
   $result     = mysql_num_rows($try);

   if($result == 0)
   {
      $page = ( 8 );
      $_SESSION['Invalid_Login_1']    = ( "true" );
   }

   else
   {
      $_SESSION['Invalid_Login_1']    = ( "false" );
      $user_info                      = mysql_query("SELECT * FROM xxxxx WHERE username = '$inlog_naam' AND password = '$wachtwoord'") or die ( mysql_error() );
      $user_info_result               = mysql_fetch_array($user_info, MYSQLI_BOTH);

      $user_lastname                  = ( $user_info_result['contact_Achternaam'] );
      $user_id                        = ( $user_info_result['user_id'] );
      $_SESSION['user_id_1']          = ( $user_id );
      $_SESSION['user_name']          = ( $inlog_naam );
      $_SESSION['user_lastname']      = ( $user_lastname );
      $session_id                     = ( session_id() );
      mysql_query("UPDATE xxxxx SET user_id = '$user_id', user_username = '$inlog_naam', user_lastname = '$user_lastname' WHERE session_id = '$session_id'") or die (mysql_error() );

      $page                           = ( 9 );

      $_SESSION['user_login']         = ( "true" );
      $_SESSION['user_main_screen']   = ( "true" );

  }

Now this part of the script works perferct, and the $_SESSION variables gets set. But when I click on the link to go to the Wizard again I got this script in the Wizard.php file to show the users personal page instead of Wizard_Step_01.php which would normally happen.

if(isset($_SESSION['user_login']) && $_SESSION['user_login'] == 'true')
{
   $page = 9;
}

else
{
   echo $_SESSION['user_login'];
}

This script doesn't seem to see the $_SESSION variable, though when I click next on this page to go to Wizard_Step_02.php it DOES recognize it.

I've also noticed that for some reason, my site is running 2 PHPSESSID's , I thought I would prevent this by doing this :

<?php if(!isset( $_SESSION )) { session_start(); } ?>

but for some reason it still creates a second PHPSESSID.

If anyone has any idea on how to disable/delete/unset 1 of the 2 PHPSESSID's if this is where the problem lies, or any idea why this is happening....

To be clear: I want to know why my page doesn't find the setted $_SESSION['user_login'] when I load the page. Also any suggestions or any form of help is appreciated.

Thanks for reading.