I don't know if it is a typo, but within your script are spaces before the <?php tag.

   <?php

this will result in an html document being delivered and your header-calls will fail. So remove the spaces and any other output before "header" calls.

You are getting error messages up there, for a quick solution try:

error_reporting(0);

I don't know if it is a typo, but within your script are spaces before the <?php tag.

   <?php

this will result in an html document being delivered and your header-calls will fail. So remove the spaces and any other output before "header" calls.

You are getting error messages up there, for a quick solution try:

error_reporting(0);

Line 28: $header is not known, this makes

$header .=

appending to a unknown variable.