Zookeeper Watcher Problem

[Giorgio Zullino]

I want information about watcher,
I must develope a MapReduce Yarn application.
I open the zookeeper connection in the main method in WordCount.java class. 
After I have a Map.java class with the map method. In map method i open a new 
zookeeper connection in this way:

final CountDownLatch connectedSignal = new CountDownLatch(1);
                    ZooKeeper zk = new ZooKeeper("localhost:2181", 30000, new 
Watcher() {
                        @Override
                        public void process(WatchedEvent event) {
                                if (event.getState() == 
Watcher.Event.KeeperState.SyncConnected) {
                                        connectedSignal.countDown();
                              }
                        }
                    });

Map class implements Watcher and i add at the end of Map class the process 
method. If i change data on the znode my process method isn’t called!
I wrong sure to set the Watcher :(