How to connect a third fragment from one fragment to the container of another fragment?

Question

Android

There is a FragmentActivity, to which several Fragments are attached via TabsPagerAdapter. In the first fragment, I created a container so that when the CheckBox is enabled on the second fragment, an additional fragment is displayed in it. I handle the OnCheckedChangeListener() event in the same fragment as the CheckBox itself. When you try to click on the CheckBox, an error occurs: he specified child already has a parent. You must call removeView() on the child's parent first.
MainActivity:

public class MainActivity extends FragmentActivity implements ActionBar.TabListener {



  private ViewPager viewPager;
  private TabsPagerAdapter mAdapter;
  private ActionBar actionBar;
    // Tab titles
  private String[] tabs = { "Расчет КВ", "Регулярность движения", "Логи", "Настройки" };

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

    // Initilization
    viewPager = (ViewPager) findViewById(R.id.pager);
    actionBar = getActionBar();
    mAdapter = new TabsPagerAdapter(getSupportFragmentManager());
        viewPager.setOffscreenPageLimit(3);
    viewPager.setAdapter(mAdapter);
    actionBar.setHomeButtonEnabled(false);
    actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);		

    // Adding Tabs
    for (String tab_name : tabs) {
      actionBar.addTab(actionBar.newTab().setText(tab_name)
          .setTabListener(this));
    }

    viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {

      @Override
      public void onPageSelected(int position) {
        // on changing the page
        // make respected tab selected
        actionBar.setSelectedNavigationItem(position);
      }

    });
  }

  @Override
  public void onTabSelected(Tab tab, FragmentTransaction ft) {
    // on tab selected
    // show respected fragment view
    viewPager.setCurrentItem(tab.getPosition());
  }
}

Fragment1_layout

<RelativeLayout
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/relativeLayout">
<LinearLayout
                android:orientation="vertical"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                <b>android:id="@+id/container"</b>
                android:layout_alignParentBottom="true"
                android:layout_centerHorizontal="true">

            </LinearLayout>

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:textAppearance="?android:attr/textAppearanceMedium"
                android:text="@string/RealTime"
                android:id="@+id/KVRealTime_tv"
                android:textSize="60dp"
                android:textStyle="bold"
                android:layout_alignParentTop="true"
                android:layout_centerHorizontal="true" />
</RelativeLayout>

Fragment2

public class Options extends Fragment implements CompoundButton.OnCheckedChangeListener {

    CheckBox EmuEnable;
    private FragmentManager manager;
    private FragmentTransaction transaction;
    private FakeSpeed fakespeed;


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        manager = getActivity().getFragmentManager();
        fakespeed = new FakeSpeed();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.fragment_options, container, false);

        EmuEnable = (CheckBox) v.findViewById(R.id.EmuEnable);
        EmuEnable.setOnCheckedChangeListener(this);
        //EmuEnable.setOnCheckedChangeListener(this);

        return v;
    }


    @Override
    public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
        transaction = manager.beginTransaction();
        if (EmuEnable.isChecked()){
            transaction.add(R.id.container, fakespeed);

        }
        transaction.commit();
    }
}

Well, the code of the third fragment, which I am trying to dynamically attach to the first one: (I will not attach the layuot code of the file, there are just a few buttons)

public class FakeSpeed extends Fragment {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {

        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View v = inflater.inflate(R.layout.fragment_fake_speed, container, true);
        return v;
    }

Answer 1

Figured out what was the problem. MainActivity was not connected through the Support library. Changed, now everything works as it should.