Cannot set a credential for principal ’sa’. (Microsoft SQL Server, Error: 15535)

For anyone on SQL Server 2005 who gets this Cannot set a credential for principal ‘sa’ error, the fix is easy, straight forward and simple…

Make sure “Map to Credential” is checked. That’s it. All you have to do is check “Map to Credential” and you’re set. For those without eyes, it’s on the bottom of the first screen where you set the user password (by right clicking the user and selecting “Properties”)

This one had me scratching my head a bit, clean install from Visual Studio 2008 (With Express 2005 Service Pack 2) and SQL 2008 SSMS