[Dovecot] Why my Evolution cannot delete emails in dovecot IMAP folder?

I use Ubuntu Hardy, get mails locally and run dovecot listening on localhost. I run Evolution and have it connect to dovecot, so that I can access my mail in IMAP and be able to use mutt from remote.

So far so good. It works. However, my problem is that Evolution cannot delete any messages. That is, when I click DELETE in Evolution, Evolution no longer sees the message , but the message is still there. That's not what I want, when deleting messages I want them to go away from Inbox.

How can I do it?

thanks

i