Android Toast message doesn't show

I know there are some other issues regard this problem, however, mine is surprisingly different (at least I think so). I guess my code is right but I don't have idea why toast message doesn't display. Firstly, I couldn't see toast message in my Fragments. Then I decided to put it in my activity and amazingly it doesn't display here too. This is code of my Activity which has been extended from FragmentActivity. ``` @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); Log.d(TAG, "***************************"); Log.d(TAG, "*** Application started ***"); Log.d(TAG, "***************************"); // assign layout to activity setContentView(R.layout.activity_main); mContext = MainActivity.this; Toast.makeText(mContext, "Hello World", Toast.LENGTH_SHORT).show(); . . . } ``` Application works fine without error and just this f.toast message doesn't display! I even replaced mContext with getApplicationContext() and I had same result, toast does not display. Any suggestion would be appreciated. Thanks =============== Update: When I open Toast class there are some red lines. please look at image below