Latiuno,
The subscriber ID you're using likely isn't right. If you update your password, it changes. There are other ways it can change too, so please check that you're using the ID that starts with "b0de". If that's not the ID you see in your Edit Profile area, let us know.
Beyond that, I'm not sure why the user wouldn't be able to login if they're account is created properly like you say. If you're using any caching, please try disabling it, especially the System - Cache plugin. If that helps, we can help you re-enable it without causing issues. If it doesn't, please let us know the URL of the site you are developing on. Please either post it here or Private Message it to me. You can PM me by clicking the arrow under my picture (<----) and hitting the mail icon.
Thanks,
Alex