need help get GPS location with at+cipgsmloc

hi ...

i try make program to get location gps from cellular operator here the script :

/*
 *Turn ON GSM at Pin12 
 *Turn on GPRS 
 *Get location with CIPGSMLOC
 *Capture Serial and print 
 *28.Sept.2016 @sonjayadotwebdotid
 *
 */
char latitude[15];
char longitude[15];
char inChar;
int index;
char inData[100];
int pinpwr = 12;
void setup()
 {
   //Init the driver pins for GSM function
    pinMode(pinpwr,OUTPUT);
    turn_ON_GSM();
    delay(15000);
    start_NET();  
    delay(5000);
 }
 void loop()    
 {    
   read_GPS_GSM();
   delay(5000);
   show_GPS();
   delay(5000);
 
 }
 void turn_ON_GSM (){
  Serial.println("Turn On GSM");
  digitalWrite(pinpwr,HIGH); //turn on at pin 12
  delay(2000);
  digitalWrite(pinpwr,LOW); //
  delay(10000);
  Serial.begin(9600); //set bautrate serial
  delay(20000);
 }
 void start_NET(){
    delay(5000);
    Serial.println("Start GPRS");
    delay(2000);
    Serial.println("AT+SAPBR=3,1,\"APN\",\"indosatgprs\""); //set apn name 
    delay(2000);
    Serial.println("AT+SAPBR=3,1,\"Contype\",\"GPRS\"");  //profile with be use
    delay(2000);
   
 }
 void read_GPS_GSM(){
    Serial.println("read GSM loc"); 
    Serial.println("AT+SAPBR=1,1"); //connected to gprs
    delay(2000);
    Serial.println("AT+CIPGSMLOC=1,1"); //get location from cellular 
    delay(3000);
    read_String(); //get out serial
    strtok(inData, ",");
    strcpy(longitude,strtok(NULL, ",")); // Gets longitude
    strcpy(latitude,strtok(NULL, ",")); // Gets latitude
    delay(2000);
    Serial.println("AT+SAPBR=0,1"); //disconneted gprs
    delay(2000);
}
 
 void show_GPS(){
          Serial.println("Show GPS data");
          Serial.println("&latitude=");
          Serial.println("&latitude=");
          Serial.print(latitude);
          Serial.print("&longitude=");
          Serial.print(longitude);
          Serial.println("\"");
          delay(2000);
     }
  
void read_String() {
      index=0;
      while(Serial.available() > 0) // Don't read unless
                                                  // there you know there is data
   {
       if(index < 50) // One less than the size of the array
       {
           inChar = Serial.read(); // Read a character
           inData[index] = inChar; // Store it
           index++; // Increment where to write next
           inData[index] = '\0'; // Null terminate the string
       }
   }
 }

but the result in serial nothing , before uploading i try with manual at command with connected to serial.

he result from serial.

Start GPRS
AT+SAPBR=3,1,"APN","indosatgprs"
AT+SAPBR=3,1,"Contype","GPRS"
read GSM loc
AT+SAPBR=1,1
AT+CIPGSMLOC=1,1
AT+SAPBR=0,1
Show GPS data
&latitude=
&latitude=
&longitude="
read GSM loc
AT+SAPBR=1,1
AT+CIPGSMLOC=1,1
AT+SAPBR=0,1
Show GPS data
&latitude=
&latitude=
&longitude="
read GSM loc
AT+SAPBR=1,1
AT+CIPGSMLOC=1,1
AT+SAPBR=0,1
Show GPS data
&latitude=
&latitude=
&longitude="

please advice and many thanks