OnBackButtonPressed pressed event not call

Hi All,

I have three page like login_page, dashboard_page and list_page

I have implemented OnBackButtonPressed event in dashboard_page and display alert message when press back button from device.

When I press twice back-button from list_page it will redirect to login_page. it will not call OnBackButtonPressed from dashboard_page,

Please suggest me how to I call OnBackButtonPressed event when back from list_page.