Quit PowerMail, delete the folder:
/Users/<username>/Library/Application Support/PowerMail
and then re-launch PowerMail. (See the How can I open the Library folder? section.) If the script files that PowerMail uses to communicate with SpamSieve are damaged, this will fix them.
Make sure that you’ve followed the instructions in the Setting Up PowerMail section.
To test that the setup works:
The setup is correct if the last entry in the log says Predicted: Spam and shows the subject for the message that you had selected. SpamSieve will be able to catch other messages like this if it’s properly configured and trained.
Otherwise, there is some other problem with PowerMail or SpamSieve. Please contact technical support and explain what happened when you followed these instructions.