Question [Q] No notification when screen of

I Just bought G2 2 days back and every thing seems to be working perfectly except for notification. I cant figure this out, when ever my screen is off I wont get notifications from email and Facebook. My email is set to push. I have checked the settings, made sure wifi is enable even during sleep. If the screen is on or im using the phone ill get the notification instantly but when turned off I wont. Reboot solves this but on for one time, after that no more email notification. I keep getting important email but am late to reply cause of this. I looked for similar thread didn't find one. Anyone got a solution