[jbpm-users] Human Task Handler and BPMN 2.0

hi i have 3 human task notation [user task] on BPMN 2.0 diagram , i set name and taskName for each user task but when add Handler for each user task , i get this error : org.drools.WorkItemHandlerNotFoundException: Could not find work item handler for Human Task when i change my custom name to "Human Task" only one handler work correctly. how can i register multiple handlers to different user task notation ? thanks for your halp