[Dovecot] Unable to get Managesieve working

[Cliff Dunn]

I have Roundcube webmail (v. 0.8.2) running with the managesieve plugin 
(v. 5.1).  I am able to create sieve rules without any problems in 
Roundcube, but incoming mail is not being processed with the rule I 
specify.  I suspect there is something that isn't configured correctly 
in dovecot, but unfortunately I am unable to find a resolution online 
and my very limited knowledge of dovecot isn't allowing me to solve this 
problem on my own.  I am including my dovecot config below.  Please keep 
my knowledge level in mind when suggesting options and let me know if 
there is any other information I can provide to help troubleshoot the 
problem.  Thanks for any assistance!

# 1.2.15: /etc/dovecot/dovecot.conf
# OS: Linux 2.6.32-5-amd64 x86_64 Debian 6.0.6
log_timestamp: %Y-%m-%d %H:%M:%S
protocols: imap imaps managesieve
ssl_cert_file: /etc/ssl/certs/postfix.pem
ssl_key_file: /etc/ssl/private/postfix.key
ssl_cipher_list: ALL:!LOW:!SSLv2
login_dir: /var/run/dovecot/login
login_executable(default): /usr/lib/dovecot/imap-login
login_executable(imap): /usr/lib/dovecot/imap-login
login_executable(managesieve): /usr/lib/dovecot/managesieve-login
mail_privileged_group: mail
mail_location: maildir:~/mail:LAYOUT=fs:INBOX=~/mail/
mbox_write_locks: fcntl dotlock
mail_executable(default): /usr/lib/dovecot/imap
mail_executable(imap): /usr/lib/dovecot/imap
mail_executable(managesieve): /usr/lib/dovecot/managesieve
mail_plugin_dir(default): /usr/lib/dovecot/modules/imap
mail_plugin_dir(imap): /usr/lib/dovecot/modules/imap
mail_plugin_dir(managesieve): /usr/lib/dovecot/modules/managesieve
auth default:
   mechanisms: plain login
   passdb:
     driver: pam
   passdb:
     driver: pam
   userdb:
     driver: passwd
   userdb:
     driver: passwd
   socket:
     type: listen
     client:
       path: /var/spool/postfix/private/auth
       mode: 432
       user: postfix
       group: postfix
plugin:
   sieve: ~/.dovecot.sieve
   sieve_dir: ~/mail/sieve