Namespace or type specified doesn't contain public member

Hi,
I have created a ASP.NET 3.5 web application and in it I have SearchGridView.vb class file in the directory Old_App_Code.  This file creates a namespace MyApp.WebControls, which is also referenced in web.config in a namespace tag, as well as included as an import directive at the beginning of my content page. 
Unfortunately, I receive the following error:
 Warning 1 Namespace or type specified in the project-level Imports 'MyApp.WebControls' doesn't contain any public member or cannot be found. Make sure the namespace or the type is defined and contains at least one public member. Make sure the imported element name doesn't use any aliases. 
Here's the first several lines of my class file SearchGridView.vb:
Imports System Imports System.Collections Imports System.Collections.Generic Imports System.ComponentModel Imports System.Text Imports System.Web I ...