Mail.app smart mailboxes

After being turned on to Merlin’s Inbox Zero presentation I’ve been rethinking my email workflow. I have been using Mail.app for a year or two now but am now just unlocking its power with regards to Smart Mailboxes. I’ve run into a couple of quick (hopefully) technical glitches which I’d love to have feedback on.

1. In trying to construct a Smart Mailbox containing messages for which I’ve recently viewed I’ve set up the following: MESSAGES that match ALL of the following: DATE LAST VIEWED is IN THE LAST 2 Days.

I only get 2 messages dropped into this mailbox (and have viewed many messages in the last 2 days). When including additional rules (Message is not in folder Junk and/or Trash) zero results return despite the 2 previous messages not being in either Junk nor Trash.

Is my perception of “Date Last Viewed” (ie. any message opened in the past x days”) different from what the app reads?

1. The second is really a similar variation of the first whereby in trying to eliminate messages that go directly to my junk folder from a Smart Mailbox that includes all messages received in the last 2 days. Even with stipulating that the messages in the “New” Smart Mailbox are not in the junk mailbox they all still appear.

Solutions appreciated. Thanks.