No Id found viewpager

Question

我有一个包含3个标签的应用。选项卡有一个带有按钮的片段，可以在同一个选项卡中转到另一个视图。我的实现很简单。我有视图寻呼机的main_activity。这是main_activity.xml的片段。

<android.support.v4.view.ViewPager
    android:id="@+id/pager"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" />

在MainActivity.java下面

public class MainActivity extends AppCompatActivity {

public SectionsPageAdapter mSectionPageAdapter;
private ViewPager mViewPager;

@Override
protected void onCreate(Bundle savedInstanceState){
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mSectionPageAdapter = new SectionsPageAdapter(getSupportFragmentManager());

    mViewPager = (ViewPager) findViewById(R.id.pager);
    setupViewPager(mViewPager);
    //Assigns the ViePager to TabLayout
    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);
}

//Defines the number of tabs by setting appropriate fragment and tab name.
private void setupViewPager(ViewPager viewPager){
    SectionsPageAdapter adapter = new SectionsPageAdapter(getSupportFragmentManager());
    adapter.addFragment(new FirsTab(),"TAB1");
    adapter.addFragment(new SecondTab(),"TAB2");
    adapter.addFragment(new ThirdTab(),"TAB3");
    viewPager.setAdapter(adapter);
    adapter.notifyDataSetChanged();

}

当我使用getChildFragmentManager（）替换带有FirsTabSubFragment的FirstTab时，我收到“找不到视图”错误。

java.lang.IllegalArgumentException: No view found for id 0x7f0d0073 (com.none.app:id/pager) for fragment FirsTabSubFragment{607b4a6 #0 id=0x7f0d0073}

在FirtTab.java的代码下面

public class FirstTab extends Fragment{

private Button btnScan;

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.scan_layout, container, false);
    btnScan = (Button) view.findViewById(R.id.btnScan);

    btnScan.setOnClickListener(new View.OnClickListener(){
        public void onClick(View view) {
            getChildFragmentManager()
                    .beginTransaction()
                    .replace(R.id.pager, new FirsTabSubFragment())
                    .addToBackStack(null)
                    .commit();
        }

    });

    return view;
}

使用getFragmentmanager（）替换会导致空视图。任何人都可以就这个话题向我提出建议吗？