Unzip file with password using SharpZipLib

I'm using SharpZipLib to compress a folder with a password without any problems. However when I look at the sample code for unzipping, VS gives me a build error saying that ZipFile does not contain a definition for Password. Here's the relevant snippet.

ZipFile zf = null;
            try
            {
                FileStream fs = File.OpenRead(archiveFilenameIn);
                zf = new ZipFile(fs);
                if (!String.IsNullOrEmpty(password))
                {

                    zf.Password = password;     // Build Error Here
                }

I was wondering whether anyone had a similar problem and solved it?