OPTIONS request while adding Authorization header - ajax

Question

Here's my problem, I'm trying to add the following Header to my GET ajax request :
Authorization: Basic XXXXXXX
So I wrote this :
function() {
var storage = window.localStorage;
var currentUsername = storage.getItem("username");
var currentPassword = storage.getItem("password");
var auth = makeBasicAuth(currentUsername, currentPassword);
$.ajaxSetup ({
beforeSend: function(request) {
request.setRequestHeader( "Authorization", auth );
}
});
I already have check the value of auth which is correct. And when I try to send my request, I get that :
OPTIONS <myurl> Error 401
Here are the headers of the request and of its answer :
Request :
Accept text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Encoding gzip, deflate
Accept-Language fr,fr-fr;q=0.8,en-us;q=0.5,en;q=0.3
Access-Control-Request-He... authorization
Access-Control-Request-Me... GET
Connection keep-alive
Host <myhost>
Origin null
User-Agent Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:22.0) Gecko/20100101 Firefox/22.0
Answer :
Access-Control-Allow-Head... Authorization
Access-Control-Allow-Meth... *
Access-Control-Allow-Orig... *
Access-Control-Max-Age 3628800
Connection Keep-Alive
Content-Encoding gzip
Content-Length 440
Content-Type text/html;charset=utf-8
Date Tue, 23 Jul 2013 13:00:58 GMT
Keep-Alive timeout=15, max=100
Server Apache-Coyote/1.1
Set-Cookie JSESSIONID=03A48D00EA04DE16396824E804E914AC; Path=/...
Vary Accept-Encoding
WWW-Authenticate Basic realm="Name Of Your Realm"
Note : I get this result whatever is the header I try to add.
Where is the problem ?
Thanks ^^.