To retrieve gzip compressed data from C#(Mono) in HttpWebRequest.GetResponse

string serialized=Json.Serialize(JsonDataDic);
HttpWebRequest request=(HttpWebRequest) WebRequest.Create("API URL");

req.ContentType="application/json; charset=UTF-8";
req.Method="POST";
req.Accept = "application/json";
req.AutomaticDecompression=DecompressionMethods.GZip |DecompressionMethods.Deflate;
req.Headers.Add(HttpRequestHeader.ContentEncoding, "gzip");
byte [] text = Encoding.UTF8.GetBytes(serialized);
byte [ ] compress=Compress(text);
req.ContentLength=compress.Length;
// Configuring Data
vars=req.GetRequestStream();
s.Write(compress,0,compress.Length);
s.Close();

HttpWebResponse wresa=(HttpWebResponse) req.GetResponse();

using(HttpWebResponse wres=(HttpWebResponse)req.GetResponse())
{
    using(Streamst=wres.GetResponseStream())
    {
        using(MemoryStream=newMemoryStream())
        {
            byte [ ] buffer = new byte [4096];
            int count = 0;
            do
            {
                count = st.Read (buffer, 0, buffer.Length);
                memoryStream.Write(buffer,0, count);

            } while(count!=0);
            string str = Encoding.UTF8.GetString(memoryStream.ToArray());

            var deserializedDoubleList=Json.Deserialize(str) as Dictionary<string, object>;;
        }
    }
}

DllNotFoundException—MonoPosixHelper
System.IO.Compression.DeflateStream..ctor (System.IO.Stream compressedStream, CompressionMode mode, Boolean leaveOpen, Boolean gzip)
(wrapper remoteing-invoke-with-check) System.IO.Compression.DeflateStream:.ctor (System.IO.Stream, System.IO.Compression.CompressionMode, boole, boolean)
System.IO.Compression.GZipStream..ctor (System.IO.Stream compressedStream, CompressionMode mode, Boolean leaveOpen)
System.IO.Compression.GZipStream..ctor (System.IO.Stream compressedStream, CompressionMode mode)
(wrapper remoteing-invoke-with-check) System.IO.Compression.GZipStream:.ctor (System.IO.Stream, System.IO.Compression.CompressionMode)
System.Net.HttpWebResponse..ctor (System.Uriuri, System.String method, System.Net.WebConnectionData, System.Net.CookieContainer container)
(wrapper remoteing-invoke-with-check) System.Net.HttpWebResponse:.ctor (System.Uri, string, System.Net.WebConnectionData, System.Net.CookieContainer)
System.Net.HttpWebRequest.SetResponseData (System.Net.WebConnectionData)
Retrow as WebException: MonoPosixHelper
System.Net.HttpWebRequest.EndGetResponse (IAsyncResult asyncResult)
System.Net.HttpWebRequest.GetResponse()