This is just a basic .NET usage question. Nothing to do with SharpCompress.
However, the reason why this isn't working is because you ought to initialize your MemoryStream with the byte array (sOut). Then wrap the MemoryStream with the DeflateStream then pass the DeflateStream to the StreamReader.
However, the reason why this isn't working is because you ought to initialize your MemoryStream with the byte array (sOut). Then wrap the MemoryStream with the DeflateStream then pass the DeflateStream to the StreamReader.