How do I authenticate against Firebase - actionscript-3

Question

I'm following this guide on how to write to my database with an authenticated user. I have set the rules properly and am able to post if all the writes are true just fine. When I pass the oauthToken I get when I follow this guide I get "Invalid claim "kid" in auth header". I've seen other questions with this result but I don't think they're doing the exact same things as I am nor are they using the same language.
So how do I authenticate properly? I can get the token and everything else just fine.
Current rule set:
{
"rules": {
"location": {
"$user_id": {
".read": all,
".write": "$user_id === auth.uid"
}
}
}
}
My code:
private function submitNewData(localId:String, authToken:String):void
{
var data:Object = new Object();
data.location = "w0.0rld";
data.description = "hello";
var request:URLRequest = new URLRequest("https://" + FIREBASE_PROJECT_ID + ".firebaseio.com/location/" + uid + ".json?auth=" + authToken);
request.data = JSON.stringify(data);
request.method = URLRequestMethod.POST;
var loader:URLLoader = new URLLoader();
loader.addEventListener(Event.COMPLETE, entrySent);
loader.load(request);
}
private function entrySent(event:flash.events.Event):void
{
trace(event.currentTarget.data); //Invalid claim 'kid' in auth header
}