[rules-users] java.lang.NullPointerException when using a custom operator

Hi all, I have been working with Drools 5.2.0 on windows xp and I have a stable project. I upgraded to windows 8, drools 5.5.0 and upgraded to eclipse Juno (from Helios). I have now encountered a strange problem with my existing drools project. I have a accustom operator called supersetof which now results in the following error reported in the IDE in any file where the supersetOf is used (LHS): Error: java.lang.NullPointerException After receving this error the drools parser does not work, hence this is the only error I have. I have tried to use the Drools 5.2.0 again (on the new windows 8 machine) but I get the same problem so I guess it has to do with some IDE\eclispe configuration or compatibility issue. Obviously not the drools project code as I have not made any changes to the working project. I did make sure the custom operator is configured similar to the way it was on my previous computer. Any ideas? Is there a different configuration for Juno? Thanks, Hezi