ASP.Net error: PostedFiles is not a member of System.Web.UI.WebControls.FileUpload

I am facing problem in the code line "For Each postedFile As HttpPostedFile In FileUpload1.PostedFiles" there is an error occured is showing "PostedFile. .... is not a member of 'System.Web.UI.WebControls.FileUpload'." under  FileUpload1.PostedFiles

Please help.

My code as below:

<div>
<asp:FileUpload ID="FileUp" runat="server"  Multiple="Multiple"/>
</div>

Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        For Each postedFile As HttpPostedFile In FileUp.PostedFiles
            Dim filename As String = Path.GetFileName(postedFile.FileName)
            Dim contentType As String = postedFile.ContentType
            Using fs As Stream = postedFile.InputStream
                Using br As New BinaryReader(fs)
                    Dim bytes As Byte() = br.ReadBytes(Convert.ToInt32(fs.Length))
                    Dim conndb As ConnectionClass = New ConnectionClass
                    Dim conString As String = conndb.getConString()
                    Using conn As New SqlConnection(constr)
                        Dim Sqlstr As String
                        If conn.State = ConnectionState.Open Then
                            conn.Close()
                        End If
                        conn.Open()
                        Sqlstr = "INSERT INTO Ads (img,word) values (@eimg,@word);"
                        Using cmd As SqlCommand = New SqlCommand(Sqlstr, conn)
                            cmd.Parameters.AddWithValue("@word", TBHeader.Text.ToString)
                            cmd.Parameters.AddWithValue("@eimg", imgByte)
                            conn.Open()
                            cmd.ExecuteNonQuery()
                            conn.Close()
                        End Using
                    End Using
                End Using
            End Using
        Next
            Response.Redirect(Request.Url.AbsoluteUri)
End Sub