spamassassin adding headers but not marking any spam?

What’s the correct way to have incoming emails flagged as spam and given a spam level? I have, for two mailboxes:

• Enable spam protection: Yes
• Discard spam: No
• Spam redirect folder: Empty for one mailbox, Junk for another (no mail ever gets put into the Junk folder except manually by me, which is what I would expect given Discard spam: No)
• Use manual procmailrc: No for one mailbox, Yes for another

Mail coming into to each mailbox is always marked:

X-Spam-Flag: NO
X-Spam-Score: 0
X-Spam-Level: 
X-Spam-Status: No, score=x tagged_above=-999 required=3 tests=[]

regardless of how spammy it is or which mailbox it goes to, which leads me to believe I’ve set something up incorrectly.

This is the procmail recipe I use for the mailbox that uses procmail; it works, but because X-Spam-Level is always empty it never triggers on spam.

:0
* !^X-Spam-Level: \*\*\*\*\*\*
* !^Precedence: bulk
* !Subject: (Re: )?\[COMIXSCHOLARS-L\]
* !^Return-Path: \<fontforge-users
* !^Subject: Ignore
{ }

:0 E:
.Ignore/
#/dev/null