Microsoft pattern and practice 3 tier architecture namespace problem

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C#

ASP.NET

architecture

Microsoft

in My project i am using micrsoft pattren and practice classes(3 tier architecture)

now in solution explorer

i have

appcode

BLL--> my own classes

DAL--> sqlhelper.cs DBBridge.cs (built in clasess)

but the problem is BLL classess are not accessing on codebehind of my aspx pages.

i have also add this namesspace projectName.BLL to my aspx page but still i cannot access my bll function ?

Sample

inside bll

clsadmin.cs (class)

<pre lang="css">using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using MCQs_Test_System.DAL;
using System.Data.SqlClient;
using System.Data;


namespace MCQs_Test_System.BLL
{
    public class admin_Program
    {
        private const string _spName = "AdminDegree";

        private DBBridge ObjDBBridge = new DBBridge();
.
..
.
...
..

and my aspx codebehind file is

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using MCQs_Test_System.BLL;


namespace MCQs_Test_System
{
    public partial class DegreeProgram : System.Web.UI.Page
    {

        protected void Page_Load(object sender, EventArgs e)
        {

        }
    }
}

you can see this

using MCQs_Test_System.BLL;

but this is showing error "bll does not exist in the namespace...