[rules-users] ClassCastExeception on some objects

Hi, When executing my rules for an object, on some objects I get a ClassCastException: java.lang.ClassCastException: org.drools.reteoo.CollectNode$CollectMemory cannot be cast to org.drools.core.util.ObjectHashMap at org.drools.reteoo.RightInputAdapterNode.assertLeftTuple(RightInputAdapterNode.java:128) (full stack-trace: http://pastie.org/877237) I've looked around in the source around where this happens, and can't figure out how it relates to my rules-file. (http://pastie.org/877238) Any pointers on how to approach this problem? Thanks! Regards, Martin Seebach