When installing the SmartPager app you are asked to allow notifications: you must click Allow.
If you clicked No, then you will receive the error. To correct this, do the following:
1. Go to the 'Settings' Application on the iPhone.
2. Click on 'Notification Center'
3. Scoll Down until you see 'SmartPager'. It should be in the 'Include' list.
4. If it's in the "Do Not Include" list, Click on the 'SmartPager Icon'.
5. Confirm 'Alert Style' is set to either Banners or Alerts
6. Make sure all other toggles are set to 'On' (green)
7. Force quit the Smart Pager app, and reopen it