Sim900 data logging through Sparkfun

I've been trying to upload data to data. Sparkfun's servers using HTTP commands, but I've hit errors every time I try.

This is my code:

#include <String.h>

void setup()
{
  Serial1.begin(9600);               // the GPRS baud rate   
  Serial.begin(9600);    // the GPRS baud rate 
  delay(500);
}

void loop()
{
  if (Serial.available())
    switch(Serial.read())
   {
     case 'h':
       SubmitHttpRequest();
       break;
       case 'j':
       http();
       break;
        } 
  if (Serial1.available())
    Serial.write(Serial1.read());
}

///SubmitHttpRequest()
///this function is submit a http request
///attention:the time of delay is very important, it must be set enough 
void SubmitHttpRequest()
{
  Serial1.println("AT+CSQ");
  delay(100);

  ShowSerialData();// this code is to show the data from gprs shield, in order to easily see the process of how the gprs shield submit a http request, and the following is for this purpose too.

  Serial1.println("AT+CGATT?");
  delay(100);

  ShowSerialData();

  Serial1.println("AT+SAPBR=3,1,\"CONTYPE\",\"GPRS\"");//setting the SAPBR, the connection type is using gprs
  delay(1000);

  ShowSerialData();

  Serial1.println("AT+SAPBR=3,1,\"APN\",\"airtelgprs.com\"");//setting the APN, the second need you fill in your local apn server
  delay(4000);

  ShowSerialData();

 // Serial1.println("AT+SAPBR=1,1");//setting the SAPBR, for detail you can refer to the AT command mamual
  //delay(2000);

  ShowSerialData();

  Serial1.println("AT+HTTPINIT"); //init the HTTP request

  delay(4000); 
  ShowSerialData();

  Serial1.println("AT+HTTPPARA=\"URL\",\"http://data.sparkfun.com/input/[public key]?private_key=[private key]&gas=24\"");// setting the httppara, the second parameter is the website you want to access
  delay(10);

  ShowSerialData();
  Serial1.print(" HTTP/1.1\r\n");
  delay(500);
  ShowSerialData();

  delay(1000);
  ShowSerialData();

  Serial1.println("AT+HTTPACTION=1");//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();

  Serial1.println("AT+HTTPREAD");// read the data from the website you access
  delay(300);

  ShowSerialData();


  Serial1.println("");
  delay(100);
}
void http()
{
  Serial1.println("AT+CGATT?");
  delay(300);
  ShowSerialData();
Serial1.println("AT+SAPBR=3,1,\"APN\",\"airtelgprs.com\"");//setting the APN, the second need you fill in your local apn server
  delay(1000); 
  ShowSerialData();

 Serial1.println("AT+CIFSR");//get local IP adress
  delay(2000); 
  ShowSerialData();

  Serial1.println("AT+CIPSPRT=0");
  delay(3000); 
  ShowSerialData();

  Serial1.println("AT+CIPSTART=\"TCP\",\"http://data.sparkfun.com\",\"80\"");//start up the connection

  delay(2000); 
  ShowSerialData();
  Serial.println();
  Serial1.println("AT+CIPSEND");//begin send data to remote server
  delay(4500);
  ShowSerialData();

  Serial1.print("PUT /input/[public key]?private_key=[private key]&gas=4");
  delay(10);
  ShowSerialData();

  Serial1.print(" HTTP/1.1\r\n");
  delay(500);
  ShowSerialData();

  Serial1.println("Host: http://data.sparkfun.com\r\n");
  delay(500);
  ShowSerialData();

  Serial1.print("Connection: keep-alive");  //working
  Serial1.print("\r\n");
  Serial1.print("\r\n");
  Serial1.println();
  delay(500);
  ShowSerialData();

Serial1.println((char)26);
  Serial1.write(0x1A);
  delay(500);//waitting for reply, important! the time is base on the condition of internet 
  Serial1.println(); 
  ShowSerialData();

  Serial1.println("AT+CIPCLOSE");//close the connection
  delay(100);
  ShowSerialData();

  Serial1.println("AT+CIPSHUT=0");
  delay(100); 
  ShowSerialData();

} 

void ShowSerialData()
{
  while(Serial1.available()!=0)
    Serial.write(Serial1.read());
}

For the first function (httprequest) I don't get a response on the server, even though the at commands all work. The second function(http) At At+CIPSEND, I get this:

ERROR

STATE: IP STATUS

CONNECT FAIL

And I've changed the URL but no luck. I still get the same response.

I'm using an Arduino Mega and a GSM SIM900