Problem moving from one state to other

[ivannoboa]

I'm having a problem moving from a state to other, this is my handler:

public final void remindActor(ActionMapping mapping, ec.gov.sri.websaleSample.presentation_layer.web_sale.RemindActorForm form, HttpServletRequest request, HttpServletResponse response) throws Exception
{

//create session factory
System.out.println("\n\n\n ****** ===> Create Session Factory" );
final org.jbpm.db.JbpmSessionFactory SESSION_FACTORY = org.jbpm.db.JbpmSessionFactory.buildJbpmSessionFactory();

//inject process definition (only once)
//final org.jbpm.graph.def.ProcessDefinition websaleUseCaseDefinition =
// org.jbpm.graph.def.ProcessDefinition.parseXmlResource("ec/gov/sri/websaleSample/presentation_layer/web_sale/websale-use-case.pdl.xml");

//final org.jbpm.db.JbpmSession session = SESSION_FACTORY.openJbpmSession();
//final org.jbpm.db.GraphSession graphSession = session.getGraphSession();

//session.beginTransaction();
//graphSession.saveProcessDefinition(websaleUseCaseDefinition);
//session.commitTransactionAndClose();

System.out.println("\n\n\n ****** ===> Create Session " );
final org.jbpm.db.JbpmSession session = SESSION_FACTORY.openJbpmSession();

System.out.println("\n\n\n ****** ===> Begin Transaction" );
session.beginTransaction() ;

System.out.println("\n\n\n ****** ===> Process Definition" );
org.jbpm.graph.def.ProcessDefinition remindActorProcess = session.getGraphSession().findLatestProcessDefinition("websaleUseCase") ;
System.out.println("\n\n\n ****** ===> Process Instance" );
org.jbpm.graph.exe.ProcessInstance remindActorInstance = new org.jbpm.graph.exe.ProcessInstance(remindActorProcess);

System.out.println("\n\n\n ****** ===> Token" );
org.jbpm.graph.exe.Token token = remindActorInstance.getRootToken();

System.out.println("\n\n\n ****** ===> Token.signal() previous" );
token. signal() ;
System.out.println("\n\n\n ****** ===> Token.signal() post" );

System.out.println("\n\n\n ****** ===> Save Process Instance" );
session.getGraphSession().saveProcessInstance(remindActorInstance) ;

System.out.println("\n\n\n ****** ===> Commit" );
session.commitTransaction() ;

System.out.println("\n\n\n ****** ===> Close" );
session.close();
}

but when I send token.signal() I got this message :

DEBUG [org.jbpm.graph.def.GraphElement] executing action 'action[sendWebOrder]'
[org.jbpm.graph.def.GraphElement] action threw exception: null
java.lang.NullPointerException
at org.jbpm.graph.def.Action.execute(Action.java:78)
at org.jbpm.graph.def.GraphElement.executeActions(GraphElement.java:186)

this is the process definition :

<process-definition name="websaleUseCase">

 <start-state name="create new web sale order" swimlane="buyer">
 <transition name="WebSale begin" to="get User Order"/>
 </start-state>

 <swimlane name="buyer">
 <assignment class="ec.gov.sri.websaleSample.presentation_layer.web_sale.BuyerAssignmentImpl"/>
 </swimlane>

 <swimlane name="salesman">
 <assignment expression="user=(ernie)"/>
 </swimlane>

 <swimlane name="accountant">
 <assignment expression="user=(bert)"/>
 </swimlane>

 <swimlane name="shipper">
 <assignment expression="user=(grover)"/>
 </swimlane>

 <node name="get User Order">
 <transition name="send web order" to="evaluate Web Order">
 <action name="sendWebOrder"/>
 </transition>
 <transition name="Main Menu" to="mainEntry">
 <action name="MainMenu"/>
 </transition>
 </node>

 <node name="fix Web Order Data">
 <transition name="info complete" to="evaluate Web Order">
 <action name="infocomplete"/>
 </transition>
 </node>

 <node name="info review">
 <transition name="incomplete" to="more info needed in">
 <action name="incomplete"/>
 </transition>
 <transition name="complete" to="mainEntry">
 <action name="complete"/>
 </transition>
 </node>

 <node name="more info needed in">
 <transition name="fix data" to="fix Web Order Data">
 <action name="fixdata"/>
 </transition>
 <timer name="complete info" duedate="20 seconds" repeat="10 seconds">
 <action name="complete info" class="ec.gov.sri.websaleSample.presentation_layer.web_sale.MoreInfoNeededImpl"/>
 </timer>
 </node>

 <end-state name="mainEntry"/>

 <task-node name="evaluate Web Order" signal="never" create-tasks="true">
 <task name="remindActor" swimlane="salesman" blocking="true">
 <controller>
 <variable name="item" access="required,read"/>
 <variable name="quantity" access="required,read"/>
 <variable name="address" access="required,read"/>
 </controller>
 </task>
 <transition name="evaluate Web Order" to="info review">
 <action name="evaluateWebOrder"/>
 </transition>
 </task-node>


</process-definition>

What I'm doing wrong, because I can see the System.out.println("\n\n\n ****** ===> Token.signal() previous" ); message but after that fails with the message above.