retrieve and cron errors

I get the following error when I click "Retrieve" on the Mailhandler::List page:
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warning: imap_open() [function.imap-open]: Couldn't open stream {mail.mydomain.com:110/pop3}INBOX in /home/mydomain/public_html/drupal/sites/all/modules/mailhandler/mailhandler.module on line 167.
warning: imap_close(): supplied argument is not a valid imap resource in /home/mydomain/public_html/drupal/sites/all/modules/mailhandler/mailhandler.retrieve.inc on line 529.
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I get the following email from cron daemon if mailhandler cron processing is enabled:
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Fatal error: Call to undefined function mailhandler_cron_retrieve() in /home/mydomain/public_html/drupal/sites/all/modules/mailhandler/mailhandler.module on line 16
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There was an email to be retrieved when the above messages were received.

I've manually tested the email account by sending email to it and retrieving said email with Outlook.

Thanks.
Steve