These are humans, not machines. They want quality. If you convince them that you fit the bill, you'll get in. Try for a different category, or post to the regional directory. The regional Yahoo reviewers want to build up their databases.
Submissions have a better chance of being included, and they get listed more quickly.
Within a few more weeks, your site may still get listed within the main Yahoo directory, as well. The Business Express program guarantees that within seven days of payment, a member of Yahoo's editorial staff will look at your site and consider it for inclusion. You receive an e-mail response within seven business days, stating whether your entry is accepted or declined. If your entry is denied, you'll be told why, and have the right to one reconsideration at no additional charge. The traffic from Yahoo is worth the effort, especially if you are a small company selling a single product.