System.Web.Silverlight not found

Description: An error occurred during the parsing of a resource required to service this request. Please review the following specific parse error details and modify your source file appropriately.

Parser Error Message: Could not load file or assembly 'System.Web.Silverlight' or one of its dependencies. The system cannot find the file specified.

Source Error:

Line 1: <%@ Page Language="C#" AutoEventWireup="true" %>
Line 2:
Line 3: <%@ Register Assembly="System.Web.Silverlight" Namespace="System.Web.UI.SilverlightControls"
Line 4: TagPrefix="asp" %>
Line 5:

Source File: aspx page

** The frustrating part is that you have checked multiple times and ensured that you have System.Web.Silverlight in your assembly and you are pointing to the correct path in the References. So how do you solve this?

According to this forum post, set the property Copy Local = True for the System.Web.Silverlight reference. Although a lot of the users cannot figure out why. Hmmm...