error: sim900 doesn't answer. check power and serial pins in gsm.cpp status=idle

hi..im really need help here.im working with sim900 quad-band gsm/gprs shield and arduino uno R3

when i uploading the program, the serial monitor always show this..

GSM Shield testing. DB:NO RESP DB:NO RESP DB:NO RESP Trying to force the baud-rate to 9600

1200 2400 4800 9600 19200 38400 57600 115200 ERROR: SIM900 doesn't answer. Check power and serial pins in GSM.cpp

status=IDLE

please help me..

Check power and serial pins in GSM.cpp

Also check the link in my signature, it may help depending on what shield you are using.

still no result I don t know where is the problem my code is correct 100%
this is the code

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

int led1 = 10;
int led2 = 11;
int led3 = 12;
int led4 = 13;

void setup()
{

Serial.begin(19200);
// set up the digital pins to control
pinMode(led1, OUTPUT);
pinMode(led2, OUTPUT);
pinMode(led3, OUTPUT);
pinMode(led4, OUTPUT);
digitalWrite(led1, LOW);
digitalWrite(led2, LOW);
digitalWrite(led3, LOW);
digitalWrite(led4, LOW);

// wake up the GSM shield
SIM900power();
SIM900.begin(19200);
delay(20000);
SIM900.print(“AT+CMGF=1\r”);
delay(100);
SIM900.print(“AT+CNMI=2,2,0,0,0\r”);

delay(100);
Serial.println(“Ready…”);
}

void SIM900power()

{
digitalWrite(9, HIGH);
delay(1000);
digitalWrite(9, LOW);
delay(7000);
}

void loop()
{
if(SIM900.available() >0)
{
inchar=SIM900.read();
if (inchar==’#’)
{
delay(10);

inchar=SIM900.read();
if (inchar==‘a’)
{
delay(10);
inchar=SIM900.read();
if (inchar==‘0’)
{
digitalWrite(led1, LOW);
}
else if (inchar==‘1’)
{
digitalWrite(led1, HIGH);
}
delay(10);
inchar=SIM900.read();
if (inchar==‘b’)
{
inchar=SIM900.read();
if (inchar==‘0’)
{
digitalWrite(led2, LOW);
}
else if (inchar==‘1’)
{
digitalWrite(led2, HIGH);
}
delay(10);
inchar=SIM900.read();
if (inchar==‘c’)
{
inchar=SIM900.read();
if (inchar==‘0’)
{
digitalWrite(led3, LOW);
}
else if (inchar==‘1’)
{
digitalWrite(led3, HIGH);
}
delay(10);
inchar=SIM900.read();
if (inchar==‘d’)
{
delay(10);
inchar=SIM900.read();
if (inchar==‘0’)
{
digitalWrite(led4, LOW);
}
else if (inchar==‘1’)
{
digitalWrite(led4, HIGH);
}
delay(10);
}
}
SIM900.println(“AT+CMGD=1,4”);
}
}
}
}
}

the line 3 is SoftwareSerial SIM900(7, 8 );

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