Windchill PDMLink 10.X 工作流表达 在 MethodServer 日志报 "java.lang.NullPointerException"

MethodServer Stacktrace :

ERROR [WfPropagationQueue.PollingThread] wt.workflow.engine.WfActivity administrator -    WfActivity.change state, exception caught (Activity Name), exception = java.lang.NullPointerException
Nested exception is: java.lang.NullPointerException
wt.util.WTException: java.lang.NullPointerException
Nested exception is: java.lang.NullPointerException
at wt.workflow.expr.WfExpression1875610661.executeSTART(WfExpression1875610661.java:494)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at wt.workflow.definer.WfExpression.executeTransition(WfExpression.java:1172)
at wt.workflow.definer.WfExpression.execute(WfExpression.java:418)
at wt.workflow.engine.WfExecutionObject.evaluateExpression(WfExecutionObject.java:769)
at wt.workflow.engine.WfActivity.changeState(WfActivity.java:923)
at wt.workflow.engine.WfActivity.changeState(WfActivity.java:202)
at wt.workflow.engine.ConnectorActivityLink.receiveEvent(ConnectorActivityLink.java:143)
at wt.workflow.engine.WfLink.receiveEventImmediate(WfLink.java:169)
at wt.workflow.engine.StandardWfEngineService.propagateEvent(StandardWfEngineService.java:858)
at sun.reflect.GeneratedMethodAccessor253.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at wt.queue.QueueEntry.execute(QueueEntry.java:231)
at wt.queue.ProcessingQueue.execEntry(ProcessingQueue.java:284)
at wt.queue.ProcessingQueue.execEntries(ProcessingQueue.java:884)
at wt.queue.PollingQueueThread.run(PollingQueueThread.java:115)
2014-05-12 09:25:24,649 ERROR [WfPropagationQueue.PollingThread] wt.queue.ProcessingQueue.WfPropagationQueue administrator - Queue entry number: 1266524014
java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor253.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at wt.queue.QueueEntry.execute(QueueEntry.java:231)
at wt.queue.ProcessingQueue.execEntry(ProcessingQueue.java:284)
at wt.queue.ProcessingQueue.execEntries(ProcessingQueue.java:884)
at wt.queue.PollingQueueThread.run(PollingQueueThread.java:115) 

Caused by: wt.workflow.engine.CannotStartException: wt.util.WTException: java.lang.NullPointerException