getting error in DataContext

Question

Hi all.
i am using linq and sqlDataAdapter to connect database and convert it into Datatable . but i get error when i declare DataContext although i also import library for references.
System.Data.Linq.DataContext context;// get error
(Error 1 The type or namespace name 'DataContext' does not exist in the namespace 'System.Data' (are you missing an assembly reference?) C:\Documents and Settings\benzema\Desktop\C#\Resort\WindowsFormsApplication1\App_Code\LinqConnection.cs 18 22 ResortApp
)
Did you know my trouble here?
Thanks and best regards.