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Can you share the URL of the competitor's site? Alan is correct that one possible cause is a site could not be indexed by OSE, but that is not the case in this situation. That would only apply to a new site or a site with very low DA. The site you list with the problem shows a PA of 49 so it should be listed in OSE. My next thought is perhaps the site is fully flash based or otherwise has a bad navigation design. If we could see the site we could offer better feedback.