If i click on device back button it should redirect to the previous page but it directly goes to the homepage of the application

Page skips while navigating through device back button.

import 'package:flutter/material.dart';
import 'package:modal_progress_hud/modal_progress_hud.dart';

class Attendance extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return AttendanceCalendar();
  }
}

class AttendanceCalendar extends State<Attendance> {
  bool isAsync = false;

  Widget build(BuildContext context) {
    return WillPopScope(
      onWillPop: _onBackButtonPressed,
      child: ModalProgressHUD(
        inAsyncCall: isAsync,
        child: Scaffold(
          appBar: AppBar(
              title: Text("Attendance");
          ),
          body: Container(),
        ),
      ),
    );
  }

  void _onBackButtonPressed() {
    Navigator.pop(context);
  }
}