arduino uno sim900 s2-1040s-z1k0c

Please help me!
I have an arduino uno and a sim900 s2-1040s-z1k0c
I would like to send sms.

It possible that this code is good, just I did something wrong, because it doesn’t work.
It stop at the init.

#include <GPRS_Shield_Arduino.h>
#include <SoftwareSerial.h>
#include <Wire.h>

#define PIN_TX 7
#define PIN_RX 8
#define BAUDRATE 9600
#define PHONE_NUMBER “+…”
#define MESSAGE “Ez egy sms arduinon keresztül”


void setup() {
while(!gprsTest.init()) {
Serial.print(“init error\r\n”);
Serial.println(“gprs init success”);
Serial.println(“start to send message …”);
gprsTest.sendSMS(PHONE_NUMBER,MESSAGE); //define phone number and text

void loop() {
//nothing to do

thank you for your help

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I would recommend checking your wiring. If you will explain how you have the SIM900 connected to the Arduino someone might be able to spot any errors you might have made.