Notification not get when app is first time installed in background

Hello,I am work on an app and i have follow all step even i get notification very nicely but i have an issue that is as follow:
1.installed app first time the notification come
2.but when is go on first time it is come in force stop mode and can't get notification
3. and when app is reopen manually is work fine
This very big problem for me,So please give me solution for how to get notification when app is in first time in background.
thankyou.