Arduino UNO Vs Arduino UNO R3

Dear All,

I am having some difficulty in using new Arduino UNO R3 shield. Previously I was using Arduino UNO to get sensor's data through SPI and transmitting it through WiFi Shield through and I was able to do it successfully. However then I ordered some more Arduino UNO Shields and now I am trying to use them for the same purpose. But I can't transmit data through WiFi shield when I use these new Arduino UNO R3 shields. Do I need to do some modification in the code? Please suggest appropriate solution. I have pasted my code which is working fine with my Old Arduino UNO Shield.

#include <SPI.h>
#include <WiShield.h>

#define WIRELESS_MODE_INFRA	1
#define WIRELESS_MODE_ADHOC	2

// Wireless configuration parameters ----------------------------------------
byte local_ip[]    = {192,168,1,203};	// IP address of WiShield
byte gateway_ip[]  = {192,168,1,1};	// router or gateway IP address
byte subnet_mask[] = {255,255,255,0};	// subnet mask for the local network
prog_char ssid[] PROGMEM    = {"SOLID"};		// max 32 bytes
unsigned char security_type = 0;	// 0 - open; 1 - WEP; 2 - WPA; 3 - WPA2

// WPA/WPA2 passphrase
const prog_char security_passphrase[] PROGMEM = {"wxst2010"};	// max 64 characters

// WEP 128-bit keys
// sample HEX keys
prog_uchar wep_keys[] PROGMEM = {	
  0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11, 0x11,	// Key 0
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	0x00,	// Key 1
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	0x00,	// Key 2
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,	0x00	// Key 3
};

// setup the wireless mode
// infrastructure - connect to AP
// adhoc - connect to another WiFi device
unsigned char wireless_mode = WIRELESS_MODE_ADHOC;
int CS_sensor = 7;
unsigned char ssid_len;
unsigned char security_passphrase_len;
//---------------------------------------------------------------------------


Server server(6000);
Client client_a;

void setup()
{
  Serial.begin(9600);
  pinMode(CS_sensor, OUTPUT);
  digitalWrite(CS_sensor, HIGH);

  // Serial.println("Starting Wifi ...");
  WiFi.begin(local_ip, gateway_ip, subnet_mask);
  // Serial.println("Wifi started.");

  server.begin();
  // Serial.println("server ready.");

  SPI.setDataMode(SPI_MODE3);
  SPI.setBitOrder(MSBFIRST);
  SPI.setClockDivider(SPI_CLOCK_DIV8);
}


void loop()
{
  // Serial.println("Start again.");
  while(!client_a.connected()){ 
    server.available(&client_a);
   // Serial.println("Hello ");
  } 

  while(client_a.connected()){    
    client_a.println("Hello !");
    // Serial.println("It's connected.");
    client_a.sendnow();
  } 
  // Serial.println("Disconnected.");
  client_a.flush();
  server.begin();
}