Same user different display name on different site collections in SharePoint 2010

I have a user let say with login: "domain\bob". I fist created a team site and the display name was "domain\bob" the user has a active user profile. Then I gave the user a display name "Bob B Bobby" in CA and create a portal site. In the portal site the user has "Bob B Bobby" as display name, the profile is also updat开发者_StackOverflow社区ed. But in the team site the display name is still "domain\bob".

How to I get the team site to update the display name to "Bob B Bobby", and why is it not done by SharePoint?

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Is it a SharePoint Foundation or SharePoint Server installation? If Server - have you enabled the user profile service application.