ViewPager не отображается для TabActivity при использовании для раздувания фрагмента

Question

как гласит заголовок. У меня есть навигация и там я раздуваю ее с помощью TabbedActivity, предварительно сделанного из галереи Android. Появляется меню вкладки, но ViewPage должен содержать другой фрагмент, а не. Как мне сделать так, чтобы это появилось?

Nav XML:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".AdminHome">
<android.support.design.widget.BottomNavigationView
    android:id="@+id/main_nav"
    android:layout_width="match_parent"
    android:layout_height="56dp"
    android:layout_alignParentBottom="true"
    android:layout_alignParentStart="true"
    android:background="@drawable/bgdw1"
    android:elevation="16dp"
    app:itemIconTint="@color/color"
    app:itemTextColor="@color/color"
    app:menu="@menu/nav_items">
</android.support.design.widget.BottomNavigationView>

<FrameLayout
    android:id="@+id/main_frame"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentStart="true"
    android:layout_above="@id/main_nav"
    android:layout_alignParentTop="true"
    >
</FrameLayout>

NavJava:

public class AdminHome extends AppCompatActivity {

private BottomNavigationView mMainNav;
private FrameLayout mMainFrame;
private AdminHomeFragment homeFragment;
private AccountFragment userFragment;
private RoomFragment roomFragment;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_admin_home);

    mMainFrame = (FrameLayout) findViewById(R.id.main_frame);
    mMainNav = (BottomNavigationView) findViewById(R.id.main_nav);

    homeFragment = new AdminHomeFragment();
    userFragment = new AccountFragment();
    roomFragment = new RoomFragment();

    setFragment(homeFragment);

    mMainNav.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            switch (item.getItemId()){

                case R.id.nav_home:
                    setFragment(homeFragment);
                    return true;
                case R.id.nav_rooms:
                    setFragment(roomFragment);
                    return true;
                case R.id.nav_account:
                    setFragment(userFragment);
                    return true;
                default: return false;
            }
        }
    });
}
private void setFragment(android.support.v4.app.Fragment fragment) {
    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    fragmentTransaction.replace(R.id.main_frame, fragment);
    fragmentTransaction.commit();
}}

TabActivity xml:

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
tools:context=".AdminHomeTabs">

<android.support.design.widget.AppBarLayout
    android:id="@+id/appbar"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:elevation="15dp"
    android:paddingTop="0dp"
    android:theme="@style/AppTheme.PopupOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:layout_weight="1"
        android:background="@drawable/bgup1"
        app:layout_scrollFlags="scroll|enterAlways"
        app:popupTheme="@style/AppTheme.PopupOverlay">
        <TextView
            android:id="@+id/toolbar_title"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:fontFamily="casual"
            android:text="Home"
            android:textColor="@color/DirtyWhite"
            android:textSize="24sp"
            android:textStyle="bold" />
    </android.support.v7.widget.Toolbar>

    <android.support.design.widget.TabLayout
        android:id="@+id/tabs"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/bgup2"
        app:tabSelectedTextColor="@color/colorAccent"
        app:tabTextColor="@color/DirtyWhite">

        <android.support.design.widget.TabItem
            android:id="@+id/tabItem"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/tab_text_1" />

        <android.support.design.widget.TabItem
            android:id="@+id/tabItem2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/tab_text_2" />

    </android.support.design.widget.TabLayout>
</android.support.design.widget.AppBarLayout>

<android.support.v4.view.ViewPager
    android:id="@+id/homenav"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior" />

TabActivity Java:

public class AdminHomeTabs extends AppCompatActivity {

/**
 * The {@link android.support.v4.view.PagerAdapter} that will provide
 * fragments for each of the sections. We use a
 * {@link FragmentPagerAdapter} derivative, which will keep every
 * loaded fragment in memory. If this becomes too memory intensive, it
 * may be best to switch to a
 * {@link android.support.v4.app.FragmentStatePagerAdapter}.
 */
private SectionsPagerAdapter mSectionsPagerAdapter;

/**
 * The {@link ViewPager} that will host the section contents.
 */
private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_admin_home_tabs);

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayShowTitleEnabled(false);
    // Create the adapter that will return a fragment for each of the three
    // primary sections of the activity.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.homenav);

    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);

    mViewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));
    tabLayout.addOnTabSelectedListener(new TabLayout.ViewPagerOnTabSelectedListener(mViewPager));
    //tabLayout.setupWithViewPager(mViewPager);

}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    //getMenuInflater().inflate(R.menu.menu_admin_home_tabs, menu);
    return true;
}

@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();

    //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";

    public PlaceholderFragment() {
    }

    /**
     * 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;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootView = inflater.inflate(R.layout.fragment_admin_home_tabs, container, false);
        TextView textView = (TextView) rootView.findViewById(R.id.section_label);
        textView.setText(getString(R.string.section_format, getArguments().getInt(ARG_SECTION_NUMBER)));
        return rootView;
    }
}

/**
 * A {@link FragmentPagerAdapter} that returns a fragment corresponding to
 * one of the sections/tabs/pages.
 */
public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        Fragment fragment = null;
        switch (position)
        {
            case 0:
                fragment = new AdminHomeTabsDash();
                break;
            case 1:
                fragment = new AdminHomeTabsNotif();
                break;
        }
        return fragment;
        // getItem is called to instantiate the fragment for the given page.
        // Return a PlaceholderFragment (defined as a static inner class below).
        //return PlaceholderFragment.newInstance(position + 1);
    }

    @Override
    public int getCount() {
        return 2;
    }
}

}

AdminHomeFragment Java:

public class AdminHomeFragment extends Fragment {

public AdminHomeFragment() {
    // Required empty public constructor
}
@Nullable
@Override
public View onCreateView(LayoutInflater inflater,@Nullable ViewGroup container,
                         @Nullable Bundle savedInstanceState) {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.activity_admin_home_tabs, container, false);
}}