Search Engines are an enigma - they have a mind of their own and don't seem to follow any rules.
Some search engines take weeks or months before they update their catalogs.
Recent reports suggest that the search engines as a group are slowing down due to the massive volume of submissions. Also, a recent bad sign is that some of the engines are requesting a hefty monthly payment to ensure your placement in the top 20 of your category. If you are not listed after about 6 weeks, you should resubmit yourself again. The first link is the main site of the search engine. The following few are different.