obj Fragment wrong 2nd argument type found 'Android.support.V4.app.Fragment.' required 'Android.app.Fragment'

I can't work out why my objFragment is giving me issues with the support manager, I'm getting this error:

 Error:(101, 17) error: no suitable method found for replace(int,android.support.v4.app.Fragment)
method FragmentTransaction.replace(int,android.app.Fragment,String) is not applicable
(actual and formal argument lists differ in length)
method FragmentTransaction.replace(int,android.app.Fragment) is not applicable
(actual argument android.support.v4.app.Fragment cannot be converted to android.app.Fragment by method invocation conversion)

And it's happening on this on objFragment on this line: .replace(R.id.container, objFragment)

Here's my full code:

import android.app.ActionBar;
import android.app.Activity;
import android.app.FragmentManager;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.widget.DrawerLayout;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.support.v4.app.Fragment;



/* public class MainActivity extends FragmentActivity {

   public static FragmentManager fragmentManager;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);

       // initialising the object of the FragmentManager. Here I'm passing getSupportFragmentManager(). You can pass getFragmentManager() if you are coding for Android 3.0 or above.
       fragmentManager = getSupportFragmentManager();
   }
} */


public class MainActivity2Activity extends FragmentActivity
        implements NavigationDrawerFragment.NavigationDrawerCallbacks {

    /**
     * Fragment managing the behaviors, interactions and presentation of the navigation drawer.
     */
    private NavigationDrawerFragment mNavigationDrawerFragment;

    /**
     * Used to store the last screen title. For use in {@link #restoreActionBar()}.
     */
    private CharSequence mTitle;

    public static android.support.v4.app.FragmentManager fragmentManager;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main_activity2);




        // initialising the object of the FragmentManager. Here I'm passing getSupportFragmentManager(). You can pass getFragmentManager() if you are coding for Android 3.0 or above.
        fragmentManager = getSupportFragmentManager();


        mNavigationDrawerFragment = (NavigationDrawerFragment)
                getFragmentManager().findFragmentById(R.id.navigation_drawer);
        mTitle = getTitle();

        // Set up the drawer.
        mNavigationDrawerFragment.setUp(
                R.id.navigation_drawer,
                (DrawerLayout) findViewById(R.id.drawer_layout));

        // initialising the object of the FragmentManager. Here I'm passing getSupportFragmentManager(). You can pass getFragmentManager() if you are coding for Android 3.0 or above.
        fragmentManager = getSupportFragmentManager();


    }

    @Override
    public void onNavigationDrawerItemSelected(int position) {

        // This method controls the navigation drawer

        Fragment objFragment = null;

        switch (position) {
            case 0:
                objFragment = new menu_1_fragment();
                break;
            case 1:
                objFragment = new menu_2_fragment();
                break;
            case 2:
                objFragment = new menu_3_fragment();
                break;
            case 3:
                objFragment = new menu_4_fragment();
                break;
            case 4:
                objFragment = new menu_5_fragment();
                break;
        }

        // update the main content by replacing fragments
        FragmentManager fragmentManager = getFragmentManager();
        fragmentManager.beginTransaction()
                .replace(R.id.container, objFragment)
                .commit();
    }

    public void onSectionAttached(int number) {
        switch (number) {
            case 1:
                mTitle = getString(R.string.title_section1);
                break;
            case 2:
                mTitle = getString(R.string.title_section2);
                break;
            case 3:
                mTitle = getString(R.string.title_section3);
                break;
            case 4:
                mTitle = getString(R.string.title_section4);
                break;
            case 5:
                mTitle = getString(R.string.title_section5);
                break;
        }
    }

    public void restoreActionBar() {
        ActionBar actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_STANDARD);
        actionBar.setDisplayShowTitleEnabled(true);
        // actionBar.setTitle(mTitle);
    }




    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (!mNavigationDrawerFragment.isDrawerOpen()) {
            // Only show items in the action bar relevant to this screen
            // if the drawer is not showing. Otherwise, let the drawer
            // decide what to show in the action bar.
            getMenuInflater().inflate(R.menu.main_activity2, menu);
            restoreActionBar();
            return true;
        }
        return super.onCreateOptionsMenu(menu);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        // Link to settings in the main menu or create google maps options
        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    /**
     * A placeholder fragment containing a simple view.
     */
    public static class PlaceholderFragment extends Fragment {
        /**
         * The fragment argument representing the section number for this
         * fragment.
         */
        private static final String ARG_SECTION_NUMBER = "section_number";

        /**
         * Returns a new instance of this fragment for the given section
         * number.
         */
        public static PlaceholderFragment newInstance(int sectionNumber) {
            PlaceholderFragment fragment = new PlaceholderFragment();
            Bundle args = new Bundle();
            args.putInt(ARG_SECTION_NUMBER, sectionNumber);
            fragment.setArguments(args);
            return fragment;
        }

        public PlaceholderFragment() {
        }

        @Override
        public View onCreateView(LayoutInflater inflater, ViewGroup container,
                                 Bundle savedInstanceState) {
            View rootView = inflater.inflate(R.layout.fragment_main_activity2, container, false);
            return rootView;
        }


        @Override
        public void onAttach(Activity activity) {
            super.onAttach(activity);
            ((MainActivity2Activity) activity).onSectionAttached(
                    getArguments().getInt(ARG_SECTION_NUMBER));
        }
    }

}