You may not have allowed enough time for the engine to index your site. The indexing time for most engines is between two days and six weeks, if they are operating normally.
Some engines have several databases they pull results from. Therefore you may be listed in one that the engine isn’t pulling from at the moment you do your search.
Frames. If you use frames on your pages, some engines cannot index frame properly. They simply “lost” the url that was submitted. Sounds ridiculous but happens more often than you think.
Hosted on a free site. Some engines will not index pages from free sites.
Anything that can be considered spamming technique. If an engine suspects any type of spamming they will may not index your page or ban your site entirely.
If your website is hosted on a server containing illegal adult content, and that site is on the black list of Google your website could be banned.
If your website is utilizing a shared IP address. All Website Source hosting plans come with a dedicated IP address for free. Some cheap web hosts do not offer static IPs. If your website is being hosted by a provider that does not offer dedicated IP addresses, your website rankings could be penalized.
