Facebook SDK 4 in Android Studio ExceptionInitializeError Login v2.3

First and foremost could someone provide me a sample that just connects and switch to another fragment when logged in that would be great so I'll have working code I can look at to understand. I'm just trying to put a Login button on a test page when the user is connected with facebook then the fragment should change. I tried what's there : http://ift.tt/1GtHi9L but I can't get it working and don't really understand what's going on.. So I'm lost. I'm having a ExceptionInitializeError with the following code. But I doubt it is correct.

My login fragment:

public View onCreateView(
        LayoutInflater inflater,
        ViewGroup container,
        Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.login_frag, container, false);

    loginButton = (LoginButton) view.findViewById(R.id.login_button);
    loginButton.setFragment(this);

    // Callback registration
    loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
        @Override
        public void onSuccess(LoginResult loginResult) {
            Toast.makeText(getActivity(),"Success",Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onCancel() {
            Toast.makeText(getActivity(),"fail",Toast.LENGTH_SHORT).show();
        }

        @Override
        public void onError(FacebookException exception) {
            Toast.makeText(getActivity(),"error",Toast.LENGTH_SHORT).show();
        }
    });
    return view;
}

MainActivity:

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    monFragmentManager = new MonFragmentManager(getSupportFragmentManager());
    monFragmentManager.showFragment(0, false);
    FacebookSdk.sdkInitialize(getApplicationContext());
    callbackManager = CallbackManager.Factory.create();
    LoginButton loginButton = (LoginButton) findViewById(R.id.login_button);
    loginButton.registerCallback(callbackManager, new FacebookCallback<LoginResult>() {
        @Override
        public void onSuccess(LoginResult loginResult) {
            monFragmentManager.showFragment(1,false);
        }

        @Override
        public void onCancel() {
            monFragmentManager.showFragment(0,false);
        }

        @Override
        public void onError(FacebookException e) {
            monFragmentManager.showFragment(0,false);
        }
    });
}