Snow Leopard Problem

I have just upgraded to Snow Leopard. I am using SpamSieve 2.8.1. I have been using this version for some time with no problems. I upgraded from Tiger. Now, SpamSieve no longer opens when Mail opens. My Rules are still intact. I still have my Junk filter turned off. My Spam folder does fill with messages, but most of them now are not spam. How can I solve this problem.

Please choose Install Apple Mail Plug-In From the SpamSieve menu.