SIM800 - HTTP GET Returns 0 value

I'm sending data to server using HTTP GET,When I run it with Serial Monitor it does send data with proper value but using an external power supply it only send 0 value

void sendHTTP(){
  sendAtCmd("AT+SAPBR=3,1,\"Contype\",\"GPRS\"", "OK", 1000);
  sendAtCmd("AT+SAPBR=3,1,\"APN\",\"internet\"", "OK", 1000);
  delay(500);
  sendAtCmd("AT+SAPBR=1,1","OK",1000);
  delay(1000);
  sendAtCmd("AT+HTTPINIT","OK",1000);
  sendAtCmd("AT+HTTP=\"CID\",1","OK",3000);
  delay(1000);
  ssGprs.print("AT+HTTPPARA=\"URL\",\"mysite.com/location.php?");
  ssGprs.print("lt="+sLat);
  ssGprs.print("&ln="+sLng);
  ssGprs.println("\"");
  delay(500);
  sendAtCmd("AT+HTTPACTION=0","HTTPACTION:0,200",30000);
}

int8_t sendAtCmd(
char*               atCmd,
char*               matchStr,
unsigned int        timeout
//Just the parameters remaining cod