SpamSieve not allowing me to erase junk messages

I probably have something configured wrong but I spent some time reconfiguring SpamSieve after I realized I had set rules up incorrectly. Now I have a Spam folder but I am unable to erase messages from it (other than individually.) The Erase Junk Mail item is greyed out. How do I erase them? What have I wrong now?

You’ve probably done nothing wrong. The Erase Junk Mail command in Apple Mail does not empty SpamSieve’s Spam mailbox. You would need to select the spam messages (e.g. using Edit > Select All) and press Delete or set Mail to automatically delete old spam messages.

Thanks for the clarification.