Why is ONE "blocked sender" continuing to appear in Inbox?

Hi -- my "blocked sender" list [Outlook 2003 Small Business Edition] works
perfectly well for moving messages to the Junk Mail folder -- except for one
particular address. The messages from that one particular "blocked sender"
continue to appear in my Inbox, and I cannot make them stop. The precise
email address of the individual shows up on my list of blocked senders in the
"Junk Mail" tab under Tools/Options. This is an individual known to me, so
it's not phishing or spam, technically -- but it's not feasible to request no
more emails. I just want them to go to Junk. Every other address I've blocked
goes to Junk; why doesn't this one, and how do I make it?

Thanks,
Kelly