POST on an Object Storage

Hello,
I would like to transfer files directly to my Object Storage from a form.
I have configured the CORS of my storage object and my GET requests are working fine. But when I want to make a POST request, I get an error: Origin X is not allowed by Access-Control-Allow-Origin. Status code: 400

My CORS configuration is:

Read ACL: .r:*,.rlistings
Write ACL: :
Meta Access-Control-Max-Age: 3600
Meta Access-Control-Expose-Headers: Meta Access-Control-Allow-Origin
Meta Access-Control-Allow-Origin: *
Content-Type: text/plain; charset=utf-8

Something is wrong ?

Thanks for your help !