Android : Post using Stackoverflow API with Facebook authentication in Android

In my android application I have to "post question" in stackoverflow website using stackexchange api. For this I am using facebook authentication to post a question in stackoverflow as a facebook user. I have created app in facebook developers network and able to login to that and get the "access_token" from facebook, and created app in stackexchange network and got the "Key" for my app. But when I am trying to post a question using https://api.stackexchange.com/docs/create-question its giving the below error. { "error_id": 400, "error_message": "key doesn't match a known application", "error_name": "bad_parameter" }

Am I following the correct procedure to post into stack overflow website as a facebook user? What is the best/correct process to do this.