[rules-users] Runtime Exception null accessor

Hello Guys, I've thought many hours about this problem, but don't know how to fix it. I've also searched the web, getting only some unfinished problems. Maybe someone here knows how to solve it: Each time I'm running JDrools through my textfiles (I'm using it in textmining concepts), I get the same runtime exception: 25.02.2013 18:03:59 org.apache.uima.collection.impl.cpm.engine.CPMThreadGroup process SCHWERWIEGEND: The CPM thread group caught the following unhandled error: java.lang.RuntimeException (Thread Name: Thread-5) 25.02.2013 18:03:59 de.fraunhofer.scai.bio.uima.core.deploy.StatusCallbackListenerImpl entityProcessComplete(151) SCHWERWIEGEND: Exception occurred java.lang.RuntimeException: Null accessor on node: a1_begin at de.fraunhofer.scai.bio.uima.core.deploy.StatusCallbackListenerImpl.entityProcessComplete(StatusCallbackListenerImpl.java:151) at org.apache.uima.collection.impl.cpm.engine.CPMThreadGroup.notifyListener(CPMThreadGroup.java:103) at org.apache.uima.collection.impl.cpm.engine.CPMThreadGroup.uncaughtException(CPMThreadGroup.java:86) at java.lang.Thread.dispatchUncaughtException(Thread.java:1888) For me it looks like an unhandeld race condition (but I'm not quite sure). Does someone have had this or a similar problem regarding null accessors at runtime? Thanks for your help. Bojan