Fragment Error : incompatible types,nécessaire android.app.fragment, mais trouvé de l'activité.messagefragment

 @Override
public void onDrawerItemSelected(View view, int position) {
    displayView(position);
}

private void displayView(int position) {
    Fragment fragment = null;
    String title = getString(R.string.app_name);
    switch (position) {
        case 0:
            fragment = new HomeFragment();
            title = getString(R.string.title_home);
            break;
        case 1:
            fragment = new FriendsFragment();
            title = getString(R.string.title_friends);
            break;
        case 2:
            fragment = new MessageFragment();
            title = getString(R.string.title_messages);
            break;
        default:
            break;
    }

l'erreur imprimés:

incompatible types,required android.app.fragment but found activity.messagefragment
InformationsquelleAutor user3409897 | 2015-09-10