Facing trouble with SIM900A and Arduino Mega while HTTP POST

Using Arduino Programming Questions
1

For last the last few days I have been working with SIM900A and Arduino mega. I am trying to send data on a sever which receive data only in application/json format. I am able to reach the server using commands for HTTP application but I am not able to post any data there. AT+HTTPDATA command is giving error. I am using following Code for this purpose. I also attached some photos showing sever is working and receiving data in json format. Serial Monitor output is there as well.

#include <SoftwareSerial.h>
#include <ArduinoJson.h>

SoftwareSerial SIM900(10, 9);

unsigned char buffer[64];
int count = 0;

void setup() {
SIM900.begin(9600);
Serial.begin(9600);
}

void loop() {

DynamicJsonBuffer jBuffer;
JsonObject& root = jBuffer.createObject();
root["message"] = "34";
char JSONmessageBuffer[33];
root.prettyPrintTo(JSONmessageBuffer, sizeof(JSONmessageBuffer));
Serial.println(JSONmessageBuffer);

Serial.println("HTTP post method :");
SIM900.println("AT");
delay(1000);
ShowSerialData();
delay(1000);

SIM900.println("AT+SAPBR=3,1,"CONTYPE","GPRS"");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+SAPBR=3,1,"APN","ufone.pinternet"");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+SAPBR=1,1");
delay(1000);
ShowSerialData();
delay(1000);

SIM900.println("AT+SAPBR=2,1");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+HTTPINIT");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+HTTPPARA="CID",1");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+HTTPPARA="URL","http://103.31.82.44/api/addData\"");
delay(1000);
ShowSerialData();
delay(1000);
SIM900.println("AT+HTTPPARA="CONTENT","application/json"");
delay(1000);
ShowSerialData();
delay(1000);

SIM900.println("AT+HTTPDATA=33,10000");
delay(5000);
ShowSerialData();
delay(5000);

SIM900.println(JSONmessageBuffer);
delay(5000);
ShowSerialData();
delay(5000);

SIM900.println("AT+HTTPACTION=1");
delay(5000);
ShowSerialData();
delay(5000);

SIM900.println("AT+HTTPTERM");
delay(5000);
ShowSerialData();
delay(5000);
SIM900.println("AT+SAPBR=0,1");
delay(5000);
ShowSerialData();
delay(5000);
}
void ShowSerialData()
{
while(SIM900.available())
{
buffer[count++]=SIM900.read();
if(count == 64) break;
}

Serial.write(buffer, count);
clearBufferArray();
count = 0;
}
void clearBufferArray()
{
for (int i=0; i<count; i++)
{
buffer*=NULL;*