Add file to Exists Zip file in windows phone

Jun 23, 2014 at 2:11 PM
Hello,
i have a project Windows phone 8 and i must add a file into a exists zip file (created with sharpziplib).
I'm write this code but not it works

public void CreateZip()
{
    using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())
    {
        if (isf.FileExists("CompressedFiles.zip")) isf.DeleteFile("CompressedFiles.zip");

        using (IsolatedStorageFileStream fsOut = new IsolatedStorageFileStream("CompressedFiles.zip", System.IO.FileMode.Create, isf))
        {
             ZipOutputStream _zipStream;
            _zipStream = new ZipOutputStream(fsOut);
            _zipStream.SetLevel(7); 
            _zipStream.Close();
        }
    }

}
private void AddFileToExistsZip(string path)
{

using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())
{

    using (IsolatedStorageFileStream fsOut = new IsolatedStorageFileStream("CompressedFiles.zip", System.IO.FileMode.Append, isf))
    {
        ZipOutputStream zipStream = new ZipOutputStream(fsOut);

        string entryName;
        entryName = ZipEntry.CleanName(path); 
        ZipEntry newEntry = new ZipEntry(entryName);
        newEntry.DateTime = DateTime.Now;

        using (IsolatedStorageFileStream stream = new IsolatedStorageFileStream(path, System.IO.FileMode.Open, isf))
        {
            newEntry.Size = stream.Length;
        }

        zipStream.PutNextEntry(newEntry);

        byte[ buffer = new byte[4096];
        using (IsolatedStorageFileStream streamReader = isf.OpenFile(path, System.IO.FileMode.Open))
        {
            StreamUtils.Copy(streamReader, zipStream, buffer);
        }
        zipStream.CloseEntry();
        zipStream.Finish();
        zipStream.Close();
    }
}
}

if i add a zip file have ONLY last file added Why?