Dear£ºBucur Marius£º
        Thank you for your help.
         As you said the presence module does not work if I disable it's module. This time I used wireshark to get the packages. I found when I disable the presence module, one point send the "Notify" packages directly to the other, and there were no changes in the watchers table. And when I enable the module, I found it can create some lists in watchers. But at this time , I found there is nothing contents in packages like "Subscribe" and "Notify".What's more when one point change the state, it dose not send any packages to the server.
         You said active_watchers will have something when the subscribe is authorised. What dose it mean? My server have not authorised the subscribe? But it can have a call with other subscribe.
         Look foreword your help. 
                                                                                                                                                          haibo  huang