You need to move the code that is creating the sessions as well and put it just below the code I gave you i.e.
<?php
//=Enable Sessions=============
if (!isset($_SESSION)) {
session_start();
}
?>
<?php
if (!session_id()) session_start();
if(isset($_POST["Insert_x"])) {
$_SESSION["Installer"] = "".((isset($_POST["wInstaller"]))?$_POST["wInstaller"]:"") ."";
}
?>
<?php
if (!session_id()) session_start();
if(isset($_POST["Insert_x"])) {
$_SESSION["Email"] = "".((isset($_POST["wInstEmail"]))?$_POST["wInstEmail"]:"") ."";
}
?>
<?php
if (!session_id()) session_start();
if(isset($_POST["Insert_x"])) {
$_SESSION["City"] = "".((isset($_POST["wInstCity"]))?$_POST["wInstCity"]:"") ."";
}
?>
<?php
if (!session_id()) session_start();
if(isset($_POST["Insert_x"])) {
$_SESSION["Type"] = "".((isset($_POST["wStyle"]))?$_POST["wStyle"]:"") ."";
}
?>
<?php
if (!session_id()) session_start();
if(isset($_POST["Insert_x"])) {
$_SESSION["Owner"] = "".((isset($_POST["wOwner"]))?$_POST["wOwner"]:"") ."";
}
?>