Header set Access-Control-Allow-Origin in .htaccess doesn't work

I can't figure out why my .htaccess header settings doesn't work.

My .htaccess file content:

Header set Access-Control-Allow-Origin *
Header always set Access-Control-Allow-Methods "POST, GET, OPTIONS, DELETE, PUT"
Header always set Access-Control-Allow-Headers "*"
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^(.*)$ index.php [QSA,L]

But when I remove Header's and add them in index.php then everything works fine.

header("Access-Control-Allow-Origin: *");
header("Access-Control-Allow-Methods: PUT, GET, POST, DELETE, OPTIONS");
header("Access-Control-Allow-Headers: *");

What am i missing?

This should work:

Header add Access-Control-Allow-Origin "*"
Header add Access-Control-Allow-Headers "origin, x-requested-with, content-type"
Header add Access-Control-Allow-Methods "PUT, GET, POST, DELETE, OPTIONS"

Just for the record, I was running into the exact same problem and none of the answers worked.

I used a headers checker tool: http://www.webconfs.com/http-header-check.php

I was testing with my IP (http://192.0.2.1/upload) and what came back was the following:

HTTP/1.1 301 Moved Permanently => 
Date => Sat, 10 Jan 2015 04:03:35 GMT
Server => Apache/2.2.21 (Win32) mod_ssl/2.2.21 OpenSSL/1.0.0e PHP/5.3.8 mod_perl/2.0.4 Perl/v5.10.1
Location => http://192.0.2.1/upload/
Content-Length => 380
Connection => close
Content-Type => text/html; charset=iso-8859-1

There was a redirection happening and the AJAX request does not honor/follow redirects.

It turned out to be the missing slash at the end of the domain (http://192.0.2.1/upload/)

I tested again with slash at the end and I got this below. Added a slash in the script too, and it was now working.

HTTP/1.1 200 OK => 
Date => Sat, 10 Jan 2015 04:03:53 GMT
Server => Apache/2.2.21 (Win32) mod_ssl/2.2.21 OpenSSL/1.0.0e PHP/5.3.8 mod_perl/2.0.4 Perl/v5.10.1
X-Powered-By => PHP/5.3.8
Access-Control-Allow-Origin => *
Access-Control-Allow-Methods => PUT, GET, POST, DELETE, OPTIONS
Access-Control-Allow-Headers => *
Content-Length => 1435
Connection => close
Content-Type => text/html

Use this tool to test if your headers are good and to troubleshoot what is happening.