ช่วยดูCode VB.net + access รันยังไม่ขึ้น interface ก็ error แล้วครับ

Imports System.Configuration
Imports WindowsApplication1.commonLayer.utilityPackage
Namespace commonLayer.utilityPackage
    Public Class config
        Public strConn As String = ConfigurationManager.ConnectionStrings("WindowsApplication1.My.MySettings.WindowsApplication1ConnectionString").ConnectionString

    End Class
End Namespace

Imports System.Data
Imports System.Data.OleDb
Imports System.Configuration
Imports WindowsApplication1.commonLayer.utilityPackage
Namespace ConnectionLayer
    Public Class ConnectionManager
        Private conString As New config
        Public Function GetDate(ByVal sSql As String) As DataTable
            Try
                Dim myAdapter As New OleDbDataAdapter(sSql, conString.strConn)
                Dim mydate As New DataTable
                myAdapter.Fill(mydate)
                Return mydate
            Catch sqlex As OleDbException
                Throw sqlex
            Catch ex As Exception
                Throw ex
            End Try
        End Function
        Public Function ExecNonQuery(ByVal strSQL As String)
            Dim cn As OleDbConnection
            cn = New OleDbConnection
            Try
                With cn
                    If .State = ConnectionState.Open Then .Close()
                    .ConnectionString = conString.strConn
                    .Open()
                End With
                Dim cmd As OleDbCommand = New OleDbCommand(strSQL, cn)
                Return cmd.ExecuteNonQuery()
            Catch sqlex As OleDbException
                Throw sqlex
            Catch ex As Exception
                Throw ex
            Finally
                cn.Close()
            End Try
        End Function
        Public Function ExecScalar(ByVal strSQL As String)
            Dim cn As OleDbConnection
            cn = New OleDbConnection
            Try
                With cn
                    If .State = ConnectionState.Open Then .Close()
                    .ConnectionString = conString.strConn
                    .Open()
                End With
                Dim cmd As OleDbCommand = New OleDbCommand(strSQL, cn)
                Return cmd.ExecuteScalar
            Catch sqlex As OleDbException
                Throw sqlex
            Catch ex As Exception
                Throw ex
            Finally
                cn.Close()
            End Try
        End Function
    End Class
End Namespace

Imports System.Data
Imports System.Data.OleDb
Imports WindowsApplication1.ConnectionLayer
Namespace ConnectionLayer
    Public Class UserManager
        Private conMng As New ConnectionManager
        Public Function getUser(ByVal userName As String, ByVal password As String) As DataTable
            Dim sqlstring As String = "SELECT Username , password from Tbl_User where Username = '" & userName & "' and password = '" & password & "'"
            Dim result As DataTable = conMng.GetDate(sqlstring)
            Return result
        End Function
    End Class
End Namespace

Imports Microsoft.VisualBasic
Imports WindowsApplication1.ConnectionLayer
Imports WindowsApplication1.ObjectLayer
Imports System.Data
Namespace BusinessLayer
    Public Class BizUser
        Private userMng As New UserManager
        Public Function getUser(ByVal userName As String, ByVal password As String) As User
            Dim objuser As New User
            Dim dtUser As DataTable = userMng.getUser(userName, password)
            If dtUser.Rows.Count > 0 Then
                objuser.Username = dtUser.Rows(0).Item("Username")
                objuser.Password = dtUser.Rows(0).Item("Password")
            End If
            Return objuser
        End Function
    End Class
End Namespace

Imports System.Data
Imports System.Data.OleDb
Imports Microsoft.VisualBasic
Imports WindowsApplication1.ObjectLayer
Imports WindowsApplication1.commonLayer.utilityPackage
Imports WindowsApplication1.BusinessLayer
Public Class Form1
    Private bizUserr As New BizUser
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim username As String = TextBox1.Text
        Dim password As String = TextBox2.Text
        Dim objUser As User = bizUserr.getUser(username, password)
        If objUser.Username = username And objUser.Password = password Then
            MsgBox("เข้าสู่ระบบ")

        End If
    End Sub
End Class

Namespace ObjectLayer
    Public Class User
        Private pUsername As String
        Private PPassword As String
        Public Property Username As String
            Get
                Return pUsername
            End Get
            Set(ByVal value As String)
                pUsername = value
            End Set
        End Property
        Public Property Password As String
            Get
                Return PPassword
            End Get
            Set(ByVal value As String)
                PPassword = value
            End Set
        End Property
    End Class
End Namespace