cannot delete polls

1. Create poll (2 options), save
2. At poll list, select poll, click "Update"

org.sakaiproject.portal.api.PortalHandlerException: uk.org.ponder.util.UniversalRuntimeException: Error invoking init method handle on bean rootHandlerBean
--> Error handling request
--> Error invoking action
--> Error invoking method processActionDelete in bean at path pollToolBean.processActionDelete
at org.sakaiproject.portal.charon.SkinnableCharonPortal.doGet(SkinnableCharonPortal.java:886)
caused by: uk.org.ponder.util.UniversalRuntimeException: Error invoking init method handle on bean rootHandlerBean
--> Error handling request
--> Error invoking action
--> Error invoking method processActionDelete in bean at path pollToolBean.processActionDelete
at org.sakaiproject.poll.service.impl.PollListManagerImpl.deletePoll(PollListManagerImpl.java:229)
at org.sakaiproject.poll.tool.params.PollToolBean.processActionDelete(PollToolBean.java:200)
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 uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:23)
at uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:17)
at uk.org.ponder.reflect.JDKReflectiveCache.invokeMethod(JDKReflectiveCache.java:77)
at uk.org.ponder.reflect.ReflectiveCache.invokeMethod(ReflectiveCache.java:141)
at uk.org.ponder.mapping.support.DARApplier.invokeBeanMethod(DARApplier.java:179)
at uk.org.ponder.rsf.state.support.RSVCApplier.invokeAction(RSVCApplier.java:218)
at uk.org.ponder.rsf.processor.support.RSFActionHandler$1.run(RSFActionHandler.java:189)
at uk.org.ponder.util.CollectingRunnableInvoker$1.run(CollectingRunnableInvoker.java:25)
at uk.ac.cam.caret.sakai.rsf.errors.ExplodingWrapper.invokeRunnable(ExplodingWrapper.java:43)
at uk.ac.cam.caret.sakai.rsf.errors.ExplodingWrapper$$FastClassByCGLIB$$84189308.invoke(<generated>:-1)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.sprin