Your e-mail indicated that the log said:
SpamSieve [Discard Spam Script] Found 0 messages in mailbox “Spam”.
So it didn’t do anything. If your Spam mailbox does in fact have messages in it, perhaps the script is not set to look in the one that you are looking at. For example, the script reads what you’ve configured in Change Settings to determine whether to look in a local or remote Spam mailbox; if the latter, it picks the Spam mailbox of the first account.