Notification gets disappeared when phone is rebooted

[kamleshdumca]

hi friends
I am working on alarms and making an app for task reminder.
I am showing notification at scheduled time by user.
But when alarm rings , notification appears . Then I switched off my phone , and again when I switched , on the notification get disappeared(doesnt show the notification).
while in the case of SMS notifiaction(default android implementation) it does not get disappeared until we drag the notification.

I want the same as like sms notification.
What should I do.
thanks.