I have a little bit of an answer maybe...
I made the game to work on Facebook.
And facebook require HTTPS links.
That's what I did.
So my AJAX Request are with the https link.
BUT, if someone is connected to facebook NOT in https, then the Request doesn't work.
basicaly, you have to be in Https to have https request that works.
being in http and make a https request will fail.
Also, being in https and making an http Request will fail.
maybe that's obvious for you, but i just discovered that.
is there a way to know in what connection is the user ?
get the Url, maybe ?
thx!