Shield Sim900 Icomsat 1.1

Hello!

I’m using the GSM shield Icomsat 1.1:

And an arduino UNO, but I have a problem.
I have a problem idk why my shield or program does not function and send me this error:

avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 1 of 10: not in sync: resp=0x00
avrdude: stk500_recv(): programmer is not responding
avrdude: stk500_getsync() attempt 2 of 10: not in sync: resp=0x00

#include <SoftwareSerial.h>;
SoftwareSerial SIM900(7, 8 );

void setup() {
SIM900.begin(19200); //Configura velocidad serial para el SIM
delay(25000); //Retardo para que encuentra a una RED
Serial.begin(19200); //Configura velocidad serial para el Arduino
Serial.println(“OK”);

}

void loop() {
SIM900.print(“AT+CMGF=1\r”); // AT command to send SMS message
delay(100);
SIM900.println(“AT+CMGS=”+525-----------""); // recipient’s mobile number, in international format
delay(100);
SIM900.println("Saludos "); // message to send
delay(100);
SIM900.println((char)26); // End AT command with a ^Z, ASCII code 26 //Comando de finalizacion
delay(100);
SIM900.println();
delay(5000); // Tiempo para que se envie el mensaje
Serial.println(“SMS sent successfully”);
}

this is part of my code, do you know why this is happening???