请教：jbpm运行中的问题：

运行带有JBPM的WEB应用，报错如下：
javax.servlet.ServletException: org.jbpm.persistence.JbpmPersistenceException: couldn't assign id to TaskInstance[AddExpenceAccount]
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:545)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:486)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
com.workflow.servlet.ChinaFilter.doFilter(ChinaFilter.java:23)
org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

root cause:
java.sql.SQLException: Field 'VERSION_' doesn't have a default value

这个可能什么原因啊？新手请教
[b]问题补充：[/b]
thank you very much ,i am tesing with your method.