Incorrect signature - Flash Facebook API [Please Help]

Question

I've spent an entire day trying to figure out how to make this error go away: Incorrect signature

I'm using as3 for my a flash file, which is embeded in iframe canva. I can connect properly:

this.fbook= new Facebook();
var webSession:WebSession = new WebSession(api_key,secret_key, session_key);
fbook.startSession(webSession);
webSession.addEventListener(FacebookEvent.CONNECT, handle1); webSession.verifySession();

but after connecting I call the getLoggedInUser method to get the uid by doing this:

var call1:FacebookCall = new GetLoggedInUser(); fbook.post(call1); call1.addEventListener(FacebookEvent.COMPLETE,handle2);

but this is giving me the incorrect signature error, I don't know how to fix it, any help?