我有3个片段，如片段A，片段B，片段C。最初片段A被加载，片段A添加片段B，类似地片段B再次添加片段C。现在，当我点击backpress或片段C中的任何按钮时，它直接显示片段A。为什么它不显示片段B？我只想删除当前片段C并显示片段B，但请帮助我。这是我的代码。

//This is FragmentA and it adds FragmentB
 fragmentManager = getSupportFragmentManager();
            fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.add(R.id.activity_main,new FragmentB());
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();

//This is FragmentB and it adds FragmentC
FragmentManager fragmentManager = getChildFragmentManager();
            FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();
            fragmentTransaction.add(R.id.publicCommunication,new FragmentC());
            fragmentTransaction.addToBackStack(null);
            fragmentTransaction.commit();

//This is FragmentC and button is available remove cuurent fragment. now here is my problem , it removes both fragmentC and FragmentB and Shows FragmentA. I want it to show FragmentC but it is not showing it shows fragmentA.
 button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                FragmentManager manager = getActivity().getSupportFragmentManager();
                 manager.popBackStackImmediate();
            }
        });