Debian (testing), procmail and qmail

I'm trying out procmail and qmail under Debian.
I can't get procmail to behave correctly with Maildir.

I have in ~/.qmail
| /usr/sbin/qmail-procmail

and in ~/.procmail

MAILDIR=$HOME/Maildir/
LOGFILE=$HOME/procmail.log

:0:
* ^To:.*plug-discuss@lists.plug.phoenix.az.us
PLUG/


However, procmail still delivers messages to /var/mail/grimiore, which
is a file, not a directory. I'm wanting it to deliver it to the PLUG
folder in my user's Maildir folder.

Any ideas?