Iseries and performance tuning D6

I have a problem with changing run-priority on my Domino tasks. I have created classes i qusrnotes, I have changed the configuration-file “domino_classes”, I have verified problems about capital letters, 2 persons have verified my setup, an ibm-person have verified it and it still dosn’t have any effect. I have seen the documentation in the Reedbook and the material from Kim Green Consulting, but still no changes. Can someone give a good advice?