activity changing doesn't work. with sherlock activity

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http://stackoverflow.com – i just make two activity, and these are sherlockActivity. i can press tab. but, doesn't change anything. below is my source. sorry. and appreciate. MainActivity.java package com.example.sherlocktest; imports; public class MainActivity extends SherlockActivity implements ActionBar.TabListener { private ActionBar aBar; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_cal); /** TabBar */ aBar = getSupportActionBar(); aBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS); aBar.setT (HowTos)