Ошибка анимации Android

После добавления анимации появилась ошибка

Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.startAnimation(android.view.animatio n.Animation)' on a null object reference at com.example.lab6.MainActivity.onCreate(MainActivity.java:48)

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        tvTitle = (TextView)findViewById(R.id.textView);
        etLog = (EditText)findViewById(R.id.editText2);
        etPass = (EditText)findViewById(R.id.editText3);
        btnEnter = (Button) findViewById(R.id.button);
        btnExit = (Button) findViewById(R.id.button2);
        mSettings = getSharedPreferences(APP_SETTINGS, Context.MODE_PRIVATE);
 
        Animation avtor = AnimationUtils.loadAnimation(this,R.anim.avt_anim); 
        tvTitle.startAnimation(avtor); //тут ошибка
        Animation tv = AnimationUtils.loadAnimation(this,R.anim.tv_enter);
        tvLog.startAnimation(tv);
        tvPass.startAnimation(tv);
        Animation et = AnimationUtils.loadAnimation(this,R.anim.et_enter);
        etLog.startAnimation(et);
        etPass.startAnimation(et);
        Animation btn = AnimationUtils.loadAnimation(this,R.anim.btn_enter);
        btnEnter.startAnimation(btn);
 
    }