problem with Properties.Settings.Default to access settings in C# windows application

Question

hi , i have C# windows app on Visual studio 2005 team system I have a connection string stored as application setting in Settings.settings file and i am trying to access it using Properties.Settings.Default but Properties keyword itself is not being recognized and i am getting a debug error Error :: The type or namespace name 'Properties' could not be found (are you missing a using directive or an assembly reference?) Any help is appreciated Yojimbo