Problems With Update WorkItem Subscribers PlugIn

Hi, i have a problem with my plugin .

A brief description how it works:

" When the workitem "defect"  changes its state in "Closed", the members with a role equal to "subscriber" ( custom role ) and  belonging to the Project Area are added as subscribers. "

The problem is :

Subscribers are properly added to the workitem working copy but the original workItem is not updated.

This is the plugin java code :

----------------------------------------------------------------------------------------------------------------------------------------------------------

public class SubscriberOnChange extends AbstractService implements IOperationParticipant {
    
 // Stati WI
 private static final String NAME_STATE_CHIUSO = "Chiuso";
 
 // Role
 private static final String ROLE_NAME_SUBSCRIBER = "subscriber";
 
 // ID WI
 private static final String WI_ID_DEF = "defect";

 // Services we need
 static private IWorkItemServer wiServer;
 private IRepositoryItemService items;
 private IContributorService contributorService;

 
 @Override
 public void run(AdvisableOperation operation,
   IProcessConfigurationElement advisorConfiguration,
   IParticipantInfoCollector collector, IProgressMonitor monitor)
     throws TeamRepositoryException {

    
   // First check that the operation was a 'save' and get he operation data
   
   Object opData = operation.getOperationData();
   if(!(opData instanceof ISaveParameter)){
    return;
   }
  
   
   // Check that this was a save operation on a work item
   
   ISaveParameter data = (ISaveParameter)opData;
   if(!(data.getNewState() instanceof IWorkItem)) {
    return;
   }
  
  
   String wfAction = data.getWorkflowAction();
   
   // Get the required service interfaces
   
   wiServer = getService(IWorkItemServer.class);
   items = getService(IRepositoryItemService.class);
   contributorService = getService(IContributorService.class);
 
   
   IWorkItem wi = (IWorkItem)data.getNewState();
   IWorkItem workItemOld =(IWorkItem)data.getOldState();
   
   
   if (!(wi.getWorkItemType().equals(WI_ID_DEF)) ){
    return;
   } 
   
   // Info workItem 
   
   Integer wiID = wi.getId();
   XMLString wiSummary = wi.getHTMLSummary();
   System.out.println("wiID : "+ wiID);
   System.out.println("wiSummury : "+ wiSummary);
   
   
   IWorkflowInfo wfInfo = wiServer.findWorkflowInfo(wi, monitor);
   String nameStateNow = wfInfo.getStateName(wi.getState2());     
   
     
   String roleName;
   
   if (nameStateNow.equalsIgnoreCase(NAME_STATE_CHIUSO)){
    roleName = ROLE_NAME_SUBSCRIBER;
   } else return;
 
    System.out.println("RoleName :"+roleName);
   
   // WorkItem Working Copy  **************************************************************************************************

   
   IWorkItem wiOnServer = wiServer.findWorkItemById(wiID,IWorkItem.FULL_PROFILE,null);
   IWorkItem wiOnServerCopy = (IWorkItem)wiOnServer.getWorkingCopy();
   

  //*********************************************************************************************************************************
   if(workItemOld!=null){ 
    
   System.out.println("Start Change subscriber section code.....");
 
     ISubscriptions subscriptions= workItemOld.getSubscriptions();
     System.out.println("Numero Subscriber WI-OLD :"+subscriptions.getContents().length);
     
    //Contributors with a role equal to "subscriber"  and  belonging to the Project Area  
   
    //The method subscribersArrayByRoleName works

     ArrayList<IContributor> subscribersArray = 

    subscribersArrayByRoleName(operation.getProcessArea(), wi, roleName, monitor);
     
    if (subscribersArray==null) return;
    if (subscribersArray.size()==0) {
         
     //Tracciatura fine esecuzione plugin
     System.out.println("END " + header);
     return;
    }
    
    //Add new subscribers to the wi workingCopy*****************************************************************************
    
    for (IContributor contr : subscribersArray){
     
      IContributorHandle user = contributorService.fetchContributorByUserId(contr.getUserId());
      wiOnServerCopy.getSubscriptions().add(user);
     
    }
   
    //*******************************************************************************************************************************
 
   //Try to Save - This section code does not work; in the log file I only see the first sys.out 
    

  try{
     
          
     System.out.println("Pre-Save......");
     
     wiServer.saveWorkItem2(wiOnServerCopy, null, null); // ??? <------------
    
     System.out.println("Post-Save.....");
    
    
    
    }catch (Exception e) {;
       
     System.out.println("ERRORE nel getService");
       
     e.printStackTrace();
    
     System.out.println(e.getMessage());
     System.out.println(e.getStackTrace());
    }} 
 }

Can you help me PLEASE???

Thanks.

Giuseppe Gravina.