Inserting variables into a database by using Arduino and gsm/gprs sim900

I have a problem with my code, it is supposed to open a url to a database and insert the variables in the database. I have already created the database and it works manually.

The code worked only one time and inserted the variables but it didn't work again and gives me an error. I haven't done anything to it then suddenly it worked again and I don't know how!! Please help me, I don't know what to do and I have a deadline.

#include <SoftwareSerial.h>

//(set up a SoftwareSerial instance called mySerial)
SoftwareSerial SIM900(2, 3);
     char URL[200]="AT+HTTPPARA=\"URL\",\"http://www.mostafafouda.com/its/de.php?lat=1&lon=5";

//(add the reading to this character array - dtostrf?)
void setup() {  
  SIM900.begin(19200);
  SIM900power();  
  Serial.begin(19200); 
  Serial.print("power up" );
  delay(20000);  


  SIM900.println("AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"");//setting the SAPBR, the connection type is using gprs
  delay(1000);
 ShowSerialData();
 SIM900.println("AT+SAPBR=3,1,\"APN\",\"etisalat\"");//setting the APN, the second need you fill in your local apn server
  delay(4000);
 ShowSerialData();
  SIM900.println("AT+SAPBR=1,1");//setting the SAPBR, for detail you can refer to the AT command mamual
  delay(2000);
 ShowSerialData();
  SIM900.println("AT+HTTPINIT"); //init the HTTP request

  delay(2000);
  ShowSerialData(); 
  SIM900.println(URL);// setting the httppara
  delay(1000);
  ShowSerialData();

  SIM900.println("AT+HTTPACTION=0");//submit the request 
  delay(10000);//the delay is very important, the delay time is base on the return from the website, if the return datas are very large, the time required longer.
 ShowSerialData();
 SIM900.println("AT+HTTPREAD");// read the data from the website you access
  delay(300);
 ShowSerialData();
  SIM900.println("");
  delay(100);}

  void SIM900power()
// software equivalent of pressing the GSM shield "power" button
{
  digitalWrite(9, HIGH);
  delay(1000);
}
void ShowSerialData()
{
  while(SIM900.available()!=0)
    Serial.write(char (SIM900.read()));
}
void loop()
{
 // Serial.println("SubmitHttpRequest - started" );
//  SubmitHttpRequest();
 // Serial.println("SubmitHttpRequest - finished" );
}