สร้าง Class สำหรับติดต่อดาต้าเบส ใน ASP.NET แต่พออัพขึ้น host กลับมองไม่เห็น เพราะอะไร ??

Compilation Error
Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately.

Compiler Error Message: CS0246: The type or namespace name 'DBConnect' could not be found (are you missing a using directive or an assembly reference?)

Source Error:

Line 15:     public partial class Index : System.Web.UI.Page
Line 16:     {
Line 17:         DBConnect DB = new DBConnect();
Line 18:         bool isLogin = false;
Line 19:                 

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Data.SqlClient;

namespace ExpenseReport
{
    public partial class DBConnect
    {
        private SqlConnection objConn;
        private SqlCommand objCmd;
        private SqlTransaction Trans;
        private String strConnString;
        private String strCommandString;
        private static String empID;
        private static String empName;

        public DBConnect()
        {
            strConnString = ConfigurationManager.ConnectionStrings["Con"].ToString();
        }

        public SqlDataReader QueryDataReader(String strSQL)
        {
            SqlDataReader dtReader;
            objConn = new SqlConnection();
            objConn.ConnectionString = strConnString;
            objConn.Open();

            objCmd = new SqlCommand(strSQL, objConn);
            dtReader = objCmd.ExecuteReader();
            return dtReader; //*** Return DataReader ***//
        }

        public DataSet QueryDataSet(String strSQL)
        {
            DataSet ds = new DataSet();
            SqlDataAdapter dtAdapter = new SqlDataAdapter();
            objConn = new SqlConnection();
            objConn.ConnectionString = strConnString;
            objConn.Open();

            objCmd = new SqlCommand();
            objCmd.Connection = objConn;
            objCmd.CommandText = strSQL;
            objCmd.CommandType = CommandType.Text;

            dtAdapter.SelectCommand = objCmd;
            dtAdapter.Fill(ds);
            return ds;   //*** Return DataSet ***//
        }

        public DataTable QueryDataTable(String strSQL)
        {
            SqlDataAdapter dtAdapter;
            DataTable dt = new DataTable();
            objConn = new SqlConnection();
            objConn.ConnectionString = strConnString;
            objConn.Open();

            dtAdapter = new SqlDataAdapter(strSQL, objConn);
            dtAdapter.Fill(dt);
            return dt; //*** Return DataTable ***//
        }
    }
}

using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Data.Common;

namespace ExpenseReport
{
    public partial class Index : System.Web.UI.Page
    {
        DBConnect DB = new DBConnect();
        bool isLogin = false;
                
        protected void Page_Load(object sender, EventArgs e)
        {

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            IsCheck(txtUsername.Text, txtPassword.Text);
        }

        private void IsCheck(string username, string password)//ตรวจสอบค่าที่รับเข้ามา
        {
            string role = "";
            string empName = "";
            string empID = "";

            string SQL = "SELECT empUsername, empPassword, empType, empID, empName FROM Employee WHERE empUsername = '" + username + "' AND empPassword = '" + password + "'";

            DataSet ds;

            ds = DB.QueryDataSet(SQL);

            if (ds.Tables[0].Rows.Count > 0)
            {
                if (username == ds.Tables[0].Rows[0]["empUsername"].ToString())
                {
                    if (password == ds.Tables[0].Rows[0]["empPassword"].ToString())
                    {
                        isLogin = true;

                        role = ds.Tables[0].Rows[0]["empType"].ToString();
                        empName = ds.Tables[0].Rows[0]["empName"].ToString();
                        empID = ds.Tables[0].Rows[0]["empID"].ToString();
                    }
                    else
                    {
                        isLogin = false;
                    }
                }
                else
                {
                    isLogin = false;
                }
            }
            else
            {
                isLogin = false;
            }

            if (isLogin)
            {
                MyTicket(username, role, empName, empID); //เรียกใช้ ticket
            }
            else
            {
                Label1.Text = "Login Failed";
            }           
        }
    }
}