Android DialogFragment вылетает из за setTitle

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        Date date = (Date) getArguments().getSerializable(ARG_DATE);
        Calendar calendar = Calendar.getInstance();
        calendar.setTime(date);
        int year = calendar.get(Calendar.YEAR);
        int month = calendar.get(Calendar.MONTH);
        int day = calendar.get(Calendar.DAY_OF_MONTH);
        View v = LayoutInflater.from(getActivity()).inflate(R.layout.dialog_date, null);
        getDialog().setTitle(getString(R.string.date_picker_title));


        mDatePicker = (DatePicker) v.findViewById(R.id.dialog_date_picker);
        mDatePicker.init(year, month, day,null);
        v.findViewById(R.id.ok_button).setOnClickListener(this);

        return v;

    }




     //Создание фрагмента
     public static DatePickerFragment newInstance(Date date) {
    Bundle args = new Bundle();
    args.putSerializable(ARG_DATE, date);
    DatePickerFragment datePickerFragment = new DatePickerFragment();
    datePickerFragment.setArguments(args);
    return datePickerFragment;
}