Zip a file from folder using ICON ZIP but empty zip created

using (Ionic.Zip.ZipFile Zip = new Ionic.Zip.ZipFile())

{

string filename = AttchmentFileName.Substring(0, AttchmentFileName.Length - 4);

string filenameE = AttchmentFileName.Substring(12);

filename = filename.Substring(12);

string zipfile = filename + ".Zip";

var zip = new ZipFile();

zip.Password = "123";

zip.Encryption = EncryptionAlgorithm.WinZipAes256;

string filenameWitoutextension = Path.GetFileNameWithoutExtension(@"C:\Template");

string destdir = @"C:\Template\" + filename + ".zip";

zip.AddEntry(filenameE, "");

zip.AddSelectedFiles(filenameE);

zip.Save(destdir);

System.Web.Mail.MailAttachment attachment = new MailAttachment(filename);

message.Attachments.Add(attachment);

}