Android : invalidateOptionsMenu doesn't work in fragment

I want to show or hide item in actionbar according to either their is text in the edit text or not

so I did the following

        seachEditText =(EditText) rootView.findViewById(R.id.nounSearch);
        seachEditText.setOnEditorActionListener(new TextView.OnEditorActionListener() {
            @Override
            public boolean onEditorAction(TextView v, int actionId, KeyEvent event) {
                if (actionId == EditorInfo.IME_ACTION_SEARCH) {
                    searchResult.Entities = new ArrayList<NounModel>();
                    _currentPage = 0;
                    categoryId = -1;
                    new GetNouns().execute();
                    return true;
                }
                else
                {
                    getActivity().invalidateOptionsMenu();
                }

                return false;
            }
        });

@Override
public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) {
    super.onCreateOptionsMenu(menu, inflater);

        if(seachEditText.getText().toString().length() > 0)
        {
            menu.findItem(R.id.action_search).setVisible(true);
        }
        else
        {
            menu.findItem(R.id.action_search).setVisible(false);
        }
}

but the actionitem never appear