Classifieds Categories

Hi,
I am having a problem with the classifieds plugin. I can't create categories. When I add a new category and save, it tells me that the category is added. Then if I go to create a new classified ad, there are no categories in the drop down list, and so can't create the classified ad.
I have checked in phpmyadmin and there is no table there for classifieds, and so I guess something went wrong there. I have uninstalled and installed the plugin several times with the same result.
Is the a SQL query I can run to create the table, or would you have a better idea of what is happening here?
Thanks.