Procmail Lockfile

[Gardner Bell]

Hi,
I'm trying to setup procmail to deliver my mail but I continuously receive the following errors in my log file.
procmail: Locking ~/Mail/Lists/FreeBSD-Questions.lock
procmail: Error while writing to "~/Mail/Lists/_YmHxxx.gardnerbell.ca"
I do receive my mail but it always ends up in the default location that I have specified.

In my .procmailrc file I have the following environment variables: 
MAILDIR=$HOME/Mail
DEFAULT=$HOME/Mail/received
PMDIR=$HOME/.procmailrc
LISTFOLDER=$HOME/Mail/Lists
SENDMAIL=/usr/sbin/sendmail

This is the recipe that fails to acquire a lock
:0:
* ^(From|To).*freebsd.org
~/Mail/Lists/FreeBSD-Questions

The permissions on my Mail and Lists directory are set to drwx------
Any help to resolve this is appreciated.

TIA

Gardner Bell