Cannot access a closed stream

[spj-uk]

I am new to SharpZipLib, having previously used Chilkat but I am having problems with the implementation.

When I call the following line I get a cannot access a closed stream error.

StreamUtils.Copy(ms, zipOutputStream, new byte[4096]);

Probably something stupid on my part :)

public static byte[] CompressFromStreamToByteArray(MemoryStream ms, string Password)
{
    try
            {
                var outputMemStream = new MemoryStream();
                using (ZipOutputStream zipOutputStream = new ZipOutputStream(outputMemStream))
                {
                    zipOutputStream.Password = Password;
                    ZipEntry entry = new ZipEntry(Password); 

                    zipOutputStream.PutNextEntry(entry);                    

                    StreamUtils.Copy(ms, zipOutputStream, new byte[4096]);
                    zipOutputStream.CloseEntry();

                    zipOutputStream.IsStreamOwner = false;                                  
                }
                outputMemStream.Position = 0;
                return outputMemStream.ToArray();

            }
            catch (Exception ex)
            {
                return null;
            }

            return null;
        }