Why I can't get GPS information on Android device

Hi!

I just follow the examples of unity, but it doesn't show any message until the waiting time (20 seconds) is out. Is the problem because of mobile phone or my code?

 public class GetLocation : MonoBehaviour
 {
 public GUIText LocationMSG;
 
 IEnumerator Start()
 {
 LocationMSG.text = myText;
 
 // First, check if user has location service enabled
 if (!Input.location.isEnabledByUser)
 {
 yield break;
 }
 
 // Start service before querying location
 Input.location.Start();
 
 // Wait until service initializes
 int maxWait = 20;
 while (Input.location.status == LocationServiceStatus.Initializing && maxWait > 0)
 {
 yield return new WaitForSeconds(1);
 maxWait--;
 }
 
 // Service didn't initialize in 20 seconds
 if (maxWait < 1)
 {
 // print("Timed out");
 LocationMSG.text = "Time out" ;
 yield break;
 }
 
 // Connection has failed
 if (Input.location.status == LocationServiceStatus.Failed)
 {
 //print("Unable to determine device location");
 LocationMSG.text = "Unable to determine device location";
 yield break;
 }
 else
 {
 LocationMSG.text = "Location: " + Input.location.lastData.latitude + " " + Input.location.lastData.longitude + " "
 + Input.location.lastData.altitude + " " + Input.location.lastData.horizontalAccuracy + " " + Input.location.lastData.timestamp ;
 
 }
 
 // Stop service if there is no need to query location updates continuously
 Input.location.Stop();
 }
 
 }