Can't compress with mono?

Question

I'm trying to compress some data in mono like this:

public static string Save(FlightProgram program, bool compressed)
{
    using (MemoryStream ms = new MemoryStream())
    {
        BinaryFormatter f = new BinaryFormatter();
        if (compressed)
        {
            using (DeflateStream gz = new DeflateStream(ms, CompressionMode.Compress))
            {
                f.Serialize(gz, program);
            }
        }
        else
        {
            f.Serialize(ms, program);
        }
        return Convert.ToBase64String(ms.ToArray()).Replace('/', '_');
    }
}

I'm simply getting the exception "CreateZStream". No inner exception. What's going on here ?

Stacktrace:

Could not save flight program: CreateZStream at   at (wrapper managed-to-native) System.IO.Compression.DeflateStream:CreateZStream (System.IO.Compression.CompressionMode,bool,System.IO.Compression.DeflateStream/UnmanagedReadOrWrite,intptr)
    at System.IO.Compression.DeflateStream..ctor (System.IO.Stream compressedStream, CompressionMode mode, Boolean leaveOpen, Boolean gzip) [0x00000] in <filename unknown>:0 
    at System.IO.Compression.DeflateStream..ctor (System.IO.Stream compressedStream, CompressionMode mode) [0x00000] in <filename unknown>:0 
    at KSPComputerModule.ProgramSerializer.Save (KSPComputer.FlightProgram program, Boolean compressed) [0x00000] in <filename unknown>:0 
    at KSPComputerModule.FPComputer.OnSave (.ConfigNode node) [0x00000] in <filename unknown>:0  (State: None)

Answer 1

Surely not relevant to the OP anymore...but I finally managed to resolve this myself. It's a bug in the Mono for Windows deployment. If you delete MonoPosixHelper.dll files from Mono/GtkSharp directories, you'll find suddenly it works. Running Process Monitor, you can see that instead of going for the mal-compiled MonoPosixHelper.dll, it now goes for libMonoPosixHelper.dll...which is compiled correctly.

So, to resolve permanently, either delete all MonoPosixHelper.dll files so it uses libMonoPosixHelper.dll...or, preferably, use a dllmap, adding

 <dllmap dll="MonoPosixHelper" target="libMonoPosixHelper.dll" os="windows" />

to either C:\Program Files (x86)\Mono\lib\mono\gac\System\4.0.0.0__b77a5c561934e089\System.dll.config(create if it doesn't already exist) or to the global Mono config at C:\Program Files (x86)\Mono\etc\mono\config