Fragment not being loaded inside FrameLayout

I created a NavigationView with 3 items, when clicking on one of them, a specific fragment should be loaded inside the FrameLayout, but this is not happening. I believe the error is in the XML, because when I select a menu item the onNavigationItemSelected method is called and falls inside the if:

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v4.widget.DrawerLayout
    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/drawer_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:openDrawer="start">


    <!-- This LinearLayout represents the contents of the screen  -->
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">

        <!-- The ActionBar displayed at the top -->
        <include
            layout="@layout/app_bar_main"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />

        <!-- The main content view where fragments are loaded -->
        <FrameLayout
            android:id="@+id/frag_container"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_below="@+id/view"/>

    </LinearLayout>

    <android.support.design.widget.NavigationView
        android:id="@+id/nav_view"
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_gravity="start"
        android:fitsSystemWindows="true"
        app:headerLayout="@layout/nav_header_main"
        app:menu="@menu/activity_main_drawer" />



</android.support.v4.widget.DrawerLayout>

MainActivity

    public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);


    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        int id = item.getItemId();

        if(item.isChecked()){
            item.setChecked(false);
        } else{
            item.setChecked(true);
        }

        if (id == R.id.nav_home) {
            PaginaInicial fragment = new PaginaInicial();
            android.support.v4.app.FragmentTransaction fragmentTrasaction =getSupportFragmentManager().beginTransaction();
            fragmentTrasaction.replace(R.id.frag_container, fragment);
            fragmentTrasaction.commit();

        } else if (id == R.id.nav_noticias) {
            Noticias fragment = new Noticias();
            android.support.v4.app.FragmentTransaction fragmentTrasaction =getSupportFragmentManager().beginTransaction();
            fragmentTrasaction.replace(R.id.frag_container, fragment);
            fragmentTrasaction.commit();

        } else if (id == R.id.nav_configuracoes) {
            Configuracoes fragment = new Configuracoes();
            android.support.v4.app.FragmentTransaction fragmentTrasaction =getSupportFragmentManager().beginTransaction();
            fragmentTrasaction.replace(R.id.frag_container, fragment);
            fragmentTrasaction.commit();

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}