I have an error when I delete an image from folder

protected void LinkButtondelete_Command(object sender, CommandEventArgs e)
        {
foreach(DataListItem item in DataListAttachfile.Items)
            {
                    string vitualpath = System.Configuration.ConfigurationManager.AppSettings["UploadPath"].ToString() + DateTime.Now.Year.ToString() + "/" + DateTime.Now.Month.ToString() + "/" + DateTime.Now.Day.ToString() + "/" + att.Duongdanfile;
                    string savepath = HttpContext.Current.Server.MapPath("/" + vitualpath);                    
                    File.Delete(MapPath(vitualpath));
            }
}

<asp:LinkButton ID="LinkButtondelete" runat="server" CommandArgument='<%# Eval("id") %>' CommandName="Select" CausesValidation="false"
                                         OnCommand="LinkButtondelete_Command">Delete</asp:LinkButton>