I have found the solution. Code was fine but I was only doing a simple logical mistake
final EditText et1 = (EditText) findViewById(R.id.etVA);
final EditText et2 = (EditText) findViewById(R.id.etVC);//that is the mistake it should be like (R.id.etVB)....
final EditText et3 = (EditText) findViewById(R.id.etVC);