Cannot access a closed Stream while creating a downloadable text file in ASP MVC 3

Im trying to prompt a downloadable text file (.txt), but I get this error:

Cannot access a closed Stream.

I have looked at simular questions in here: Cannot Access Closed Stream But it was not very useful.

Here is my code:

    private FileStreamResult Export()
    {
        string name = "filename.txt";

        MemoryStream stream = new MemoryStream();
        using (StreamWriter writer = new StreamWriter(stream))
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("A text...");
            writer.WriteLine(sb.ToString());
        }

        return File(stream, "text/plain", name);
    }

UPDATE (working copy):

This gives me an blank text file.

private FileResult Export()
{
    string name = "filename.txt";

    MemoryStream stream = new MemoryStream();
    StreamWriter writer = new StreamWriter(stream);

    StringBuilder sb = new StringBuilder();
    sb.Append("A text...");
    writer.WriteLine(sb.ToString());

    writer.Flush();
    stream.Seek(0, SeekOrigin.Begin);

    return File(stream, "text/plain", name);
}