Error ASP.NET

Error    1    Type ‘HtmlTextWriter’ is not defined.

SOLVE :
Imports System.Web.UI

Error    5    Type ‘HttpContext’ is not defined.    D:\…..\FormRewriter.vb
SOLVE : Add Reference to project with System.Web

Error    1    Could not load type ‘PageBase’.

SOLVE :
http://anandganesh2005.blogspot.com/2011/02/could-not-load-type-pagebase.html