Does anyone know how to configure the heuristic option in Symantec Premium Anti Spam?

I have deployed Symantec's Premium Anti Spam on an SBS box with Exchange running. The heuristic option is grayed out. There is no option for creating custom policies either. The user manuals are okay but a bit lacking in answering questions. This is version 5 as an add on for the Premium Groupware. License is activated and showing 344 days left but only the default settings are changeable. Settings for SPAM detection is set at 25 but still an awful lot of SPAM is making it through. I am using some standard RBL providers for the whitelist/blacklist. If I can figure out how to turn the heuristic levels on I could gain some measure of control.