ActionBar Sherlock not showing up. What might be the error?

Question

I included ActionBarSherlock as a library. Added this in manifest.xml:

<application android:icon="@drawable/ic_launcher" android:label="@string/app_name"
 android:theme="@style/Theme.Sherlock">

This is what I wrote in my activity:

FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
            DialogFragment newFragment = new DialogFragment();
            newFragment.setArguments(getIntent().getExtras());
            ft.add(android.R.id.content, newFragment, "dialog");
                ft.commit();

            getSupportFragmentManager();

Still, the action bar doesn't show up. Any small sample code would help or remarks as to where I am going wrong should help.