This happened to me too, when I tried to publish my 5th hub. I couldn't work out what I had done wrong. I emailed team@hubpages (after first going through HubPages for some help - in the help section, or asking questions, or in the forum). I did get a reply from HubPages via email 4 days later, apologizing for the inconvenience, which I appreciated) but wha also happened is that about three or four hours after first trying to publish the article, it did actually go through. So I'm not sure what was wrong, but I'm happy it went through. You may find some more immediate answers here https://hubpages.com/faq/ and scroll down to the "Hubs" section.