login failed?

Hi all, My apologies if this has been answered already; I was looking for a search function for this mailing list, to no avail.

Running RH8.

I've just installed rcube and I can't log in. Every attempt yields "Login Failed". The imap server is running fine (I can use other clients without problem). I'm wondering about this host setting:

$rcmail_config['default_host'] = '';

I've tried entering my server's hostname, and "localhost", but the result is the same.

My maillog log shows that a login attempt is made, but that's it. Can anyone give me a pointer for other things to consider in troubleshooting this problem?

Thanks! Aaron.