#6 error in showing output

[Sourabh Wadhwa]

I am using asp.net 2.0 and am trying to use Open Flash Charts but when i'm trying to build the solution i'm grtting error "Could not load file or assembly 'System.Web.Extensions, Version=3.5.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' or one of its dependencies. The system cannot find the file specified. "