PHP Error: Unable to connect to managesieve on localhost:4190

Trying to properly configure “managesieve” plugin for RounCube webmail. After enabling the plugin the error log gives:

[13-Apr-2014 19:08:04 -0700]: PHP Error: Unable to connect to managesieve on localhost:4190 in /home/user/public_html/plugins/managesieve/lib/Roundcube/rcube_sieve_engine.php on line 191 (GET /?_task=settings&_action=plugin.managesieve) [13-Apr-2014 19:08:04] Not currently in AUTHORISATION state (1): [13-Apr-2014 19:08:04] Not currently connected (1):

The instructions on http://www.sunfinedata.com/tutorial/enable-the-managesieve-of-dovecot-and-use-it-in-roundcubemail didn’t help. Has anyone successfully configured RoubCube auto-response on Virtualmin servers?