As I recall, when we publish a Hub a message comes up saying that the Hub will have to be examined and, if okay, will be published within twenty-four hours. Maybe you didn't wait long enoug before checking. So, check again now.
If that is not the reason then obviously there is something holding it back. It could be something technical or it could be something to do with the quality of the Hub. For example, it might not be considered long enough.
Whatever it is, it will be something programmed by the Hubpages people. Read the rules on placing Hubs and keep trying. That's about all I can think of at this stage.