I can't google authentication with Android app

public class LoginActivity extensions AppCompatActivity{
    private static final int REQUEST_CODE_SIGN_IN=9001;

    private FirebaseAuth firebaseAuth;
    public static GoogleApiClient googleAPIClient;

    private DatabaseReference usersRef;

    private ProgressDialog progressDialog;

    private GoogleApiClient.OnConnectionFailedListener onConnectionFailedListener=newGoogleApiClient.OnConnectionFailedListener(){
        @ Override
        public void onConnectionFailed(@NonNullConnectionResult connectionResult){
            Toast.makeText(LoginActivity.this, "Google Play Services error.", Toast.LENGTH_SHORT).show();
        }
    };

    @ Override
    public void onCreate (Bundle savedInstanceState) {
        System.out.println("***LoginActivity.onCreate-start");
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_login);

        try{
            progressDialog = new ProgressDialog(this);

            GoogleSignInOptions options=new GoogleSignInOptions.Builder (GoogleSignInOptions.DEFAULT_SIGN_IN)
                    .requestIdToken(getString(R.string.default_web_client_id))
                    .requestEmail()
                    .build();

            GoogleAPICclient=newGoogleApiClient.Builder(this)
                    .enableAutoManage(this, onConnectionFailedListener)
                    .addApi(Auth.GOOGLE_SIGN_IN_API, options)
                    .build();

            firebaseAuth=FirebaseAuth.getInstance();
        } catch(Exceptione){
            e.printStackTrace();
        }
        System.out.println("***LoginActivity.onCreate-start");
    }

    @ Override
    public void onStop() {
        System.out.println("LoginActivity.onStop-start");
        if(null!=usersRef){
            usersRef.removeEventListener(valueEventListener);
        }
        super.onStop();
    }

    public void onCancelButtonClick (View view) {
        finish();
    }

    public void onLoginButtonClick (View view) {
        System.out.println("***LoginActivity.onLoginButtonClick-start");
        Intent=Auth.GoogleSignInApi.getSignInIntent(googleAPIClient);
        startActivityForResult(intent,REQUEST_CODE_SIGN_IN);
        System.out.println("***LoginActivity.onLoginButtonClick-end");
    }

    @ Override
    public void onActivityResult(int requestCode, int resultCode, Intent data){
        super.onActivityResult(requestCode, resultCode, data);
        System.out.println("***LoginActivity.onActivityResult-start");

        if(requestCode==REQUEST_CODE_SIGN_IN){
            System.out.println("***LoginActivity.onActivityResult-in if");
            GoogleSignInResult result=Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            if(result.isSuccess()){
                System.out.println("***LoginActivity.onActivityResult-in if success";
                GoogleSignInAccount=result.getSignInAccount();
                firebaseAuthWithGoogle(account);
            } else{
                System.out.println("***LoginActivity.onActivityResult-in error");
                System.out.println("***LoginActivity.onActivityResult-in error state:"+result.getStatus().getStatusMessage());
                Toast.makeText(LoginActivity.this, "Error:" +result.getStatus().getStatusMessage(), Toast.LENGTH_SHORT).show();
            }
        }
        System.out.println("***LoginActivity.onActivityResult-end");
    }

    public void firebaseAuthWithGoogle(GoogleSignInAccount account){
        // firebase authentication
    }
}