For long time i am trying to figure out why Yahoo is not ranking my website. But till yet i could not explore the real reason behind it. I have seen one strange think in Yahoo SERPs. When ever i search with my website's domain name in Yahoo US datacenter it shows website's url without www. But if when i search in some other country datacenter, Yahoo SERPs shows website url with www. Why this is happening? Is it the real problem that my website is not getting rank in Yahoo?