Zip the folder is not working first time C# and DotNetZip

Question

I have a DotNetZip code for zipping the folder. It doesnt zip the file for the first time after cleaning the solution. After that it works fine. Can anybody know the issue why its happening??

Button Click Event Code

private void button3_Click(object sender, EventArgs e)
{
    try
    {
        copy_stuff(textBox1.Text, textBox2.Text, textBox3.Text);
    }

    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

Method that gets called from Button Click

private void copy_stuff(string srcFolder, string destFolder, string Backup)
{
    using (ZipFile zip = new ZipFile())
    {
        zip.AddProgress += AddProgressHandler;
        zip.CompressionLevel = Ionic.Zlib.CompressionLevel.Default;
        zip.SaveProgress += SaveProgress;
        zip.StatusMessageTextWriter = System.Console.Out;
        zip.AddDirectory(destFolder);
        zip.Save(Backup + "\\VibrantBackup" + DateTime.Now.ToString("yyyyMMdd hh.mm.ss") + ".zip");
        label1.Text = "Compression completed.";
    }
}

Add & Save Handlers for Progress

    int _numEntriesToAdd = 0;
    int _numEntriesAdded = 0;
    void AddProgressHandler(object sender, AddProgressEventArgs e)
    {
        switch (e.EventType)
        {
            case ZipProgressEventType.Adding_Started:
                _numEntriesToAdd = 0;
                _numEntriesAdded = 0;
                label1.Text = "Adding files to the zip...";
                label1.Update();
                Application.DoEvents();
                break;
            case ZipProgressEventType.Adding_AfterAddEntry:
                _numEntriesAdded++;
                label1.Text = String.Format("Adding file: {0} :: {2}",
                                         _numEntriesAdded, _numEntriesToAdd, e.CurrentEntry.FileName);
                label1.Update();
                Application.DoEvents();
                break;
            case ZipProgressEventType.Adding_Completed:
                label1.Text = "Added all files";
                label1.Update();
                Application.DoEvents();
                break;
        }
    }

    public void SaveProgress(object sender, SaveProgressEventArgs e)
    {
        if (e.EventType == ZipProgressEventType.Saving_Started)
        {
            label1.Text = "Begin Saving: " + e.ArchiveName;
            label1.Update();
            Application.DoEvents();
        }
        else if (e.EventType == ZipProgressEventType.Saving_BeforeWriteEntry)
        {
            label1.Text = "Processing : " + e.CurrentEntry.FileName;
            label1.Update();
            label3.Text = "Files Processed: (" + (e.EntriesSaved + 1) + "/" + e.EntriesTotal + ")";
            label3.Update();
            Application.DoEvents();
            progressBar3.Maximum = e.EntriesTotal;
            progressBar3.Value = e.EntriesSaved + 1;
        }
        else if (e.EventType == ZipProgressEventType.Saving_EntryBytesRead)
        {
            //progressBar2.Value = (int)((e.BytesTransferred * 100) / e.TotalBytesToTransfer);
            //label3.Text = "Writing: " + e.CurrentEntry.FileName + " (" + (e.EntriesSaved + 1) + "/" + e.EntriesTotal + ")";
            label1.Update();
            Application.DoEvents();
        }

    }