Is your site too shallow?
To ensure that your site is not too shallow you want incoming links to as many of your websites' pages as possible. The search engines see incoming links as a good thing and if they're going to a lot of different pages in your site, that's even better.
A site with inbound links only coming to a single page alerts the search engines that you may have used spam-like software or 'bots' to get those links in the first place. A shallow site is going to have a lot more trouble ranking and getting than its deep-linked counterparts.
How deep are the links to your website?