Not Receiving the flex sensor data

Trying to transmit flex sensor via rf module , but unable to receive , the rx pin in the Uno is not glowing whereas tx led in mega is glowing , so can any one please help with the code .
here's the tx code

int ledPin = 13;
int flexSensorPin = 0;
int val1 = 0;
int rx =0;
int tx =1;


void setup() {
pinMode(ledPin, OUTPUT);
pinMode(rx, INPUT);
pinMode(tx, OUTPUT);
Serial.begin(4800);
}

void loop()
{
val1 = analogRead(flexSensorPin);
val1 = map(val1, 150,400,100,0);
delay(250);
Serial.println(val1);
}

successfully seeing the values in serial monitor with tx led on .

here's the rx code

#include <SoftwareSerial.h>

SoftwareSerial RFSerial(2, 3); //'virtual' rx pin, 'virtual' tx pin

void setup()  
{
 Serial.begin(4800);
 RFSerial.begin(4800);
}

void loop()                     // run over and over again
{
 if (RFSerial.available()) {
     Serial.print((char)RFSerial.read());
 }
}

have even tried with various codes at receiver side such as

/*
SimpleReceive
This sketch displays text strings received using VirtualWire
Connect the Receiver data pin to Arduino pin 11
*/
#include <VirtualWire.h>
byte message[VW_MAX_MESSAGE_LEN]; // a buffer to store the incoming messages
byte messageLength = VW_MAX_MESSAGE_LEN; // the size of the message
void setup()
{
Serial.begin(9600);
Serial.println("Device is ready");
// Initialize the IO and ISR
vw_setup(2000); // Bits per sec
vw_rx_start(); // Start the receiver
}
void loop()
{
if (vw_get_message(message, &messageLength)) // Non-blocking
{
Serial.print("Received: ");
for (int i = 0; i < messageLength; i++)
{
Serial.write(message[i]);
}
Serial.println();
}
}

the above code is for the tx code

/*
SimpleSend
This sketch transmits a short text message using the VirtualWire library
connect the Transmitter data pin to Arduino pin 12
*/
#include <VirtualWire.h>
int flexSensorPin = A0;
char flex[8];
void setup()
{
// Initialize the IO and ISR
vw_setup(2000); // Bits per sec
Serial.begin(9600);
}
void loop()
{
int flexSensorReading = analogRead(flexSensorPin); 

  Serial.println(flexSensorReading);


  //In my tests I was getting a reading on the arduino between 512, and 614. 
  //Using map(), you can convert that to a larger range like 0-100.
  int flex0to100 = map(flexSensorReading, 150,400,100,0);
  Serial.println(flex0to100);
  itoa(flex0to100,flex,20);
   delay(250); //just here to slow down the output for easier reading
}
void send (int flex0to100)
{
 vw_send((uint8_t *)flex, strlen(flex));
vw_wait_tx(); // Wait until the whole message is gone
}

Have you tried the sender and receiver examples, to verify that your modules and wiring is okay?

Your last sketch doesn't send anything.

So your problem is not with the Flex Sensor, it is that you cannot successfully transmit data from your transmitter unit to your receiver by whateer means you have chosen.
Are you simply connecting the 2 arduinos together with wire or are you attempting to use some sort of transmitter/receiver pair ?
A rough schematic would help you get some answers here. Even a photo of a hand drawn picture.

Also, on top of what the others have said, what's the 20 in this for?:-
itoa(flex0to100,flex,20);itoa

I am just a starter , in the code section , i am using the rf module 434 mhz ..
It is working with the basic sample programs like hello world , and other , nut reading the sensor data and transmitting it isn't .
the above program , is by modifying the potentiometer reading inot flex reading and transmitting that
but not able to .. receive
I see the tx led lit , but not the rx led on the receiver using uno and mega