问FragmentTransaction.replace（）不起作用应如何解决？

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    Fragment frag = null;

    // Right now I only have code for the addCourse() fragment, will add more soon
    switch (item.getItemId()) {
    case R.id.addCourse:
        frag = new AddCourseFragment();
        break;
    default:
        return super.onOptionsItemSelected(item);
    }

    // The support library is being dumb and replace isn't actually 
    getFragmentManager().beginTransaction()
        .remove(this).add(getId(), frag).addToBackStack(null).commit();
    return true;

}

public class AddCourseFragment extends Fragment {

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_addcourse, container, false);
//      if (view.findViewById(R.id.timesFrame)!=null) {
        Fragment timesFrag = new TimesFragment();
        getChildFragmentManager().beginTransaction()
            .add(R.id.timesFrame, timesFrag).commit();
//      }
    return view;
    }
}