This can be related to the network carrier and the actual phone's internal GPS; neither of which the app can actually control. To take advantage of the app's features you must be at the business, however as experienced if the phone cannot accurately locate itself this can lead to reduced functionality. The first steps is ensuring the phone's location services are active. However the phones WiFi can also be used to assist the phone to triangulate it's location. Even if the phone is not actually connected to a WiFi network the phone will use nearby WiFi networks to more accurately determine its location.
The combination of 'active' location services and the phone's WiFi will lead to an improvement in the phone's GPS accuracy. You can check this by reviewing the position on the phone's standard mapping App before and after WiFi and location services are activated.
Furthermore, if the patron has not 'Allowed' all Facebook permissions during the initial download process this can impact their ability to Check-in. To reauthorise their app with Facebook the customer will have to do the following:
- Login on their private Facebook account
- 'Search' - You app name
- Remove app
Now the customer can use Facebook Connect to log back into your app and attempt complete the check in promotion.