ESP8266 as UDP server in AP mode

While I find it easy to configure the ESP8266 to send UDP packets in Station Mode I am finding it difficult to do the same in AP mode. The code below goes up to the stage of creating the Soft AP but nothing happens after that… any idea what is going wrong ? I want to just beam up four integer variables to a listening UDP receiver once every 20millisecond. SO was first trying to establish the link …

What is wrong in the code below :

#include <ESP8266WiFi.h> // Used for the soft AP
#include <WiFiUdp.h>     // used for UDP comms.

WiFiUDP Udp;

const char *APssid = "ESP8266-AP";
const char *APpassword = ""; 

//*************************

void setup() {

  Serial.begin(9600);              //fire up the serial port
 
  WiFi.mode(WIFI_AP_STA);

  Serial.print("Soft-AP IP address = ");
  Serial.println(WiFi.softAPIP()); // Confirm AP IP address
}
//**************************

void loop() {

  Udp.beginPacket((255,255,255,255), 52971);
  Udp.write(millis());
  Udp.endPacket();
}
//**************************