Most probably you are using iOS 8.0+. There is a change regarding location services.
I'm pasting part of our documentation:
Note (iOS): For iOS there is a change introduced in 8.0 version that changes the way location service is requested. There are two modes for using location service from an application (WhenInUse - denotes using location service only when application is running, and Always mode which allows using location service in a background application). According to business scenario location service request could be done via requestWhenInUseAuthorization or requestAlwaysAuthorization methods. Both methods require a specific setting in your application to be set in application.plist file. Application plist file should contain NSLocationWhenInUseUsageDescrition or NSLocationAlwaysUsageDescription
string values respectively. For iOS versions below 8.0 there is a similar string value named NSLocationUsageDescription which is not mandatory.
If there is no string that describes why application wants to use location services, location services will not be granted with iOS 8.0+.