Probably you are not using proper syntax for your website, or the username is wrong. It doesn’t check for spaces in the URL, so be careful. I suppose I should add some url checks for the preference. Format right now must be http://www.site.com/
Another problem could be your plugins location or some such thing. It’s relying on everything being where it should be. Might help to get a logcat – there is most likely an error there.