Sim900(wont receive messages)

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1

Hi
My sim900 won't receive messages, i can't figure out why.
After that i need to find out how i get it to reply to my messages automatically.
It says:

GSM Shield testing.
DB:NO RESP

Please help

#include "SIM900.h"
#include <SoftwareSerial.h>
//If not used, is better to exclude the HTTP library,
//for RAM saving.
//If your sketch reboots itself proprably you have finished,
//your memory available.
//#include "inetGSM.h"

//If you want to use the Arduino functions to manage SMS, uncomment the lines below.
#include "sms.h"
SMSGSM sms;
char pos;

//To change pins for Software Serial, use the two lines in GSM.cpp.

//GSM Shield for Arduino
//www.open-electronics.org
//this code is based on the example of Arduino Labs.

//Simple sketch to send and receive SMS.

int numdata;
boolean started=false;
char smsbuffer[160];
char str1[16];
char str2[16];
char n[20];

void setup()
{
     //Serial connection.
     Serial.begin(9600);
     Serial.println("GSM Shield testing.");
     //Start configuration of shield with baudrate.
     //For http uses is raccomanded to use 4800 or slower.
     if (gsm.begin(2400)) {
          Serial.println("\nstatus=READY");
          started=true;
     } else Serial.println("\nstatus=IDLE");

     if(started) {
          //Enable this two lines if you want to send an SMS.
          if (sms.SendSMS("5010", "balance"))
          Serial.println("\nSMS sent OK");
     }

     sms.DeleteSMS(sms.IsSMSPresent(SMS_UNREAD));
};

void loop()
{
     if(started) {
          //Read if there are messages on SIM card and print them.
        /**  deprecated method
        if(gsm.readSMS(smsbuffer, 160, n, 20)) {
               Serial.println(n);
               Serial.println(smsbuffer);
          }
          **/

          
          //get 1st sms
          sms.GetSMS(sms.IsSMSPresent(SMS_UNREAD),n,20,smsbuffer,160);
          Serial.println(n);
          Serial.println("Beskeden:");
          Serial.println(smsbuffer);

          strcpy(str1, smsbuffer);
          strcpy(str2, "gps");

          //sms.SendSMS("51503577", "test");
          Serial.println("--------------------------");
          Serial.println(str1);
          Serial.println(str2);
          Serial.println("--------------------------");

          if (strcmp(str1, str2) == 0) {
            sms.SendSMS(n, "test");
            Serial.println("\nSMS sent OK");
          }
          
          delay(3000);

          //sms.DeleteSMS(sms.IsSMSPresent(SMS_UNREAD));
     }
};