Facebook chat reports "not-authorized", although "xmpp_login" is granted - facebook

Question

I am trying to integrate the facebook chat into our mobile Flash/AIR application, and am using XIFF for the XMPP stuff. Of course, I had to modify some files for the newer Facebook API that uses access_token instead of sig and secret.
For those familiar with the xiff/smack API, here is how I establish the connection:
XFacebookPlatform.setFacebookSessionValues(AppData.FACEBOOK_APP_ID, AppData.getInstance().getFBSession().accessToken);
XMPPConnection.registerSASLMechanism("X-FACEBOOK-PLATFORM", XFacebookPlatform);
var con :XMPPConnection = new XMPPConnection();
con.server = "chat.facebook.com";
con.useAnonymousLogin = true;
con.connect(XMPPConnection.STREAM_TYPE_STANDARD);
.
Basically, I get to the point where I answer the challenge with what IMO should be a correct format:
var responseMap:Dictionary = new Dictionary();
responseMap.api_key = fb_api_key;
responseMap.call_id = 0;
responseMap.method = incomingChallengeMap.method;
responseMap.nonce = incomingChallengeMap.nonce;
responseMap.access_token = user_access_token;
responseMap.v = "1.0";
var challengeResponse:String = "api_key=" + responseMap.api_key;
challengeResponse += "&call_id=" + responseMap.call_id;
challengeResponse += "&method=" + responseMap.method;
challengeResponse += "&nonce=" + responseMap.nonce;
challengeResponse += "&access_token=" + responseMap.access_token;
challengeResponse += "&v=" + responseMap.v;
challengeResponse = Base64.encode( challengeResponse );
.
The response is sent, but as an answer I receive the following:
<failure xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
<not-authorized xmlns="urn:ietf:params:xml:ns:xmpp-sasl"/>
This sounds like I did not grant the "xmpp_login", but I did. I checked that via the Graph API explorer, and for the same access_token it shows:
{
"data": [
{
"installed": 1,
"xmpp_login": 1,
"user_online_presence": 1,
"friends_online_presence": 1
}
]
}
This should be more than enough, I guess.
But still I get the "not-authorized" failure.
Any ideas what went wrong here?

Answer 1

Funny enough, the problem was this line:
var con :XMPPConnection = new XMPPConnection();
Which has to be replaced with this line:
var con :XMPPTLSConnection = new XMPPTLSConnection();
That's it. The facebook chat only authenticates with a TLS connection.
.
While that does make sense, the error message of
<failure xmlns="urn:ietf:params:xml:ns:xmpp-sasl">
<not-authorized xmlns="urn:ietf:params:xml:ns:xmpp-sasl"/>
is very misleading here, as it implies that something with the rights would be wrong.