Authenication Code

I’m trying to add some AD authentication code to my application and am getting some errors such as:


Error      1      Type 'System.DirectoryServices.DirectoryEntry' is not defined.      
Error      2      Type 'System.DirectoryServices.DirectorySearcher' is not defined.
Error      3      Name 'DirectoryServices' is not declared.      
Error      4      Type 'System.DirectoryServices.SearchResult' is not defined.

Did they change this in VS2005?

Code found on the Net:

    Private Function ValidateActiveDirectoryLogin(ByVal Domain As String, ByVal Username As String, ByVal Password As String) As Boolean
        Dim Success As Boolean = False
        Dim Entry As New System.DirectoryServices.DirectoryEntry("LDAP://" & Domain, Username, Password)
        Dim Searcher As New System.DirectoryServices.DirectorySearcher(Entry)
        Searcher.SearchScope = DirectoryServices.SearchScope.OneLevel
        Try
            Dim Results As System.DirectoryServices.SearchResult = Searcher.FindOne
            Success = Not (Results Is Nothing)
        Catch
            Success = False
        End Try
        Return Success
    End Function