Action @BeginTask fails after redirect.execute() from JBPM event

[aconn7]

I am getting this error:

Caused by: java.lang.IllegalStateException: task/process id may not be null
at org.jboss.seam.bpm.BusinessProcessInterceptor.getProcessOrTaskId(BusinessProcessInterceptor.java:159)

When I post to an @BeginTask annotated action:

        @BeginTask @EndTask
        public String completeReject(){
                return "success";
        }

via:

<h:commandButton  action="#{rfcJbpmTask.completeReject}" value="COMPLETE REJECT" >
        <f:param name="taskId" value="#{taskInstance.id}"  />
</h:commandButton>

The page is initially rendered via redirect after a task has been successfully completed and the graph token traverses to the next task.  The node-enter event fires this:

        public void doRedirectIfSameActor(String page){
                // Conditional redirect if current actor is who it being assigned.  This is triggered on task-assign
                String taskActorId = taskInstance.getActorId();
                if (taskActorId.equalsIgnoreCase(actor.getId())){
                        redirect.setViewId(page);
                        redirect.setParameter("taskId",taskInstance.getId());
                        redirect.setParameter("id", taskInstance.getVariable("documentId"));
                        redirect.execute();
                }
                
        }

The BusinessProcessInterceptor is firing this error:

 private Long getProcessOrTaskId(String paramName, String el)
   {
      Object id;
      if ( Strings.isEmpty(paramName) )
      {
         id = Expressions.instance().createValueExpression(el).getValue();
      }
      else
      {
/////// FALLS INTO THIS CASE HERE:  values has only null values ////////////////
         String[] values = Parameters.instance().getRequestParameters().get(paramName);
         id = values!=null && values.length==1 ? values[0] : null;*
      }
      
      if (id==null)
      {
         throw new IllegalStateException("task/process id may not be null");
      }
      else if (id instanceof Long)
      {
         return (Long) id;
      }
      else if (id instanceof String)
      {
         return new Long( (String) id );
      }
      else
      {
         throw new IllegalArgumentException("task/process id must be a string or long");
      }
    }
}

Can any explain what is happening?  It appears to me that the initial rendering of my form is not working property in that the h:commandButton parameters hare not included.  But this is a guess.

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WHAT I AM TRYING TO ACCOMPLISH

I would like to be able to associate a form with a JPDL task node so that when the user completes 1 task, the next task node's events handler can auto-render the next applicable form.

I like the idea of associating the form with the jpdl <node>.  This way, the navigation is bound to the graph and is automatically updated when the graph is updated.  If I defined my navigation elsewhere, I have 2 things I need to keep in sync.  PageFlow definitions do not apply here because I am talking about a page flow that spans multiple tasks.

I have seen this technique (navigating via the node-enter event) used by Exadel in their E7 product so I am guessing it can be done.

Help appeciated!

Thanks