Two Way Communication with "nRF24.h"

Hey, is there anyone who knows how to use the nRF24.h Library?

i need to make two way communications between two arduino's to simulate an authentication handshake before the data is transmitted.

i have one way communication working just fine.

i have tried using "if (isAckPayloadAvailable())" but i cannot get it to work.

The Code Snippets attached shows what i am trying to achieve.

Node 1 :

void loop()
{
  if (digitalRead(Button)) 
  {
    myRadio.stopListening();
    digitalWrite(Led, HIGH);
// Sending Hello

// Receiving HelloAck

// Sending Ack

// Sending Data
    dataTransmitted = random (1000000000,2147483647);
    myRadio.write( &dataTransmitted, sizeof(dataTransmitted) );
// Receiving DataAck

// Show Data Outputs
    Serial.println(helloAck);
    Serial.println("");

    Serial.println("Data Sent :");
    Serial.println(dataTransmitted);
    Serial.println("");

    Serial.println(dataAck);
    Serial.println("");
// LED off
    Serial.println("...");
    delay(200);
    digitalWrite(Led, LOW);
  }
}

Node 2 :

void loop()
{
  myRadio.startListening();
  if (myRadio.available()) 
  {
    digitalWrite(Led, HIGH);
// Receiving Hello

// Sending HelloAck

// Receiving Ack

// Receiving Data
    myRadio.read( &dataReceived, sizeof(dataReceived) );
// Sending DataAck

// Show Data Outputs
    Serial.println(hello);
    Serial.println("");

    Serial.println(ack);
    Serial.println("");

    Serial.println("Data Received :");
    Serial.println(dataReceived);
    Serial.println("");

    Serial.println(dataAck);
    Serial.println("");
// LED off
    Serial.println("...");
    delay(500);
    digitalWrite(Led, LOW);
  }
}

Robin2's RF24 tutorial.