Fix error b77a5c561934e089 Net2 CLR C# Stored Procedure SQL 2008 on Server 2008R2

General information for the business: Software development
Kind of development: Customization of existing program
Description of requirements/functionality: I need to call a WEB service from SQL server. The attachment spHTTPRequest.sql contains a stored procedure that works provided that the string returned by sp_OAMethod does not exceed 4000 (or 8000?) characters. Do overcome this limitation I wrote a SQL CLR procedure and my attempt is shown in the attachment POSTWebRequest.cs using the .NET Framework 2.0. I am not a C# programmer so the code may incomplete. The dll was incorporated into SQL 2008 using the attached BuildWebRequest.sql file.

When using test data that works with spHTTPRequest I am getting the following error via Server Manager

Request for the permission of type 'System.Net.WebPermission, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089' failed.

A Google search indicated that it is a security problem but I couldnt see how to solve it, or it could be that their is an error in the C# code.

Server 2008 R2 STandard Service Pack 1
SQL Server 2008 10.50.4020.0
Microsoft .NET Framework 4.5.2 (4.5.51209)
Microsoft SQL Server System CLR Types (x64) 10.52.4000.0
.NET Framework 3.5.1 feature installed
Specific technologies required: SQL Server C# net2
OS requirements: Windows
Extra notes: