MemoryStream output to a file c#

I have below code:

string fileName = GetFileName();
using (var stream = new MemoryStream())
{
    using (var sw = new StreamWriter(stream))
    {            
        for (int i = 0; i < 20; i++)
        {
            sw.WriteLine(String.Format("{0};{1};{2};{3};{4};{5}", i.ToString(), (i*2).ToString(), "-_-_-", "-_" + i.ToString() + "_-", "3", "15"));
        }

        // Check if compression needed.
        if (stream.Length > limit)
        {
            sw.Flush();
            stream.Position = 0;

            using (Ionic.Zip.ZipFile zipFile = new Ionic.Zip.ZipFile())
            {
                absoluteFileName = Path.GetFileName(fileName);
                zipFile.AddEntry(absoluteFileName, stream);

                zipFileName = Path.Combine(Path.GetDirectoryName(fileName), Path.ChangeExtension(absoluteFileName, ZipExtension));
                zipFile.Save(zipFileName);
            }
        }
        else
        {
            // no compression needed
            using (FileStream file = new FileStream(fileName, FileMode.Create, System.IO.FileAccess.Write))
            {
                byte[] bytes = new byte[stream.Length];
                stream.Read(bytes, 0, (int)stream.Length);
                file.Write(bytes, 0, bytes.Length);
                //stream.Close();
            }
        }
    }

I am trying to generate a plain text file in case memorystream length (in bytes) is no greater than a concrete amount of bytes (limit (see conditional).

If memorystream length is greater than a concrete amount of bytes then I create a zipped file.

My problem is in the else body when I try to write all the content of memory stream into a plain text file when no need to compress (stream.Length <= limit). I get a file of 39bytes but when I open it, it is empty, only new lines within it.

I do this because I do not want to create the file on disk directly in case I need to compress it. So if at the end no need to compress, I write all the streammemory to a file and that is the problem, file is empty, only newlines.

What am I doing wrong?

UPDATE2 I have put below line just before conditional:

 sw.Flush();
 stream.Position = 0;

And now the content is written to file.