New Post: Executing R.net in a restricted AppDomain

Executing R.net in the same appdomain works great. Now, I want to have it run in a separate restricted appdomain. This throws the following exception:

System.TypeLoadException was unhandled
HResult=-2146233054
Message=Inheritance security rules violated by type: 'RDotNet.NativeLibrary.UnmanagedDll'. Derived types must either match the security accessibility of the base type or be less accessible.
Source=RBugReplication
TypeName=RDotNet.NativeLibrary.UnmanagedDll
StackTrace:

   at RBugReplication.Program.CreateREngine()
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at RBugReplication.Program.Main(String[] args) in c:\Users\For\Documents\Visual Studio 2013\Projects\RBugReplication\RBugReplication\Program.cs:line 35
   at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)
   at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

InnerException:

Here is the code the replicates the issue. All projects are built against .net 4.0. The project references RDotNet and RDotNet.Native library located in its 'lib' folder.

    class Program
    {
        static void Main(string[] args)
        {
            SetupPath();

            var ps = new PermissionSet(PermissionState.None);
            ps.AddPermission(new SecurityPermission(PermissionState.Unrestricted));
            ps.AddPermission(new FileIOPermission(PermissionState.Unrestricted));
            ps.AddPermission(new ReflectionPermission(PermissionState.Unrestricted));
            ps.AddPermission(new EnvironmentPermission(PermissionState.Unrestricted));

            var appDomain = AppDomain.CreateDomain(
                "sandbox",
                new Evidence(),
                AppDomain.CurrentDomain.SetupInformation,
                ps);

            appDomain.DoCallBack(LoadAssemblies);

            appDomain.DoCallBack(CreateREngine);
        }

        public static void SetupPath()
        {
            var oldPath = Environment.GetEnvironmentVariable("PATH");
            var rPath = @"C:\Program Files\R\R-3.0.2\bin\x64";
            var newPath = string.Format("{0}{1}{2}", rPath, Path.PathSeparator, oldPath);
            Environment.SetEnvironmentVariable("PATH", newPath);
        }

        private static void LoadAssemblies()
        {
            LoadDll(@"..\..\lib\RDotNet.NativeLibrary.dll");
            LoadDll(@"..\..\lib\RDotNet.dll");
        }

        private static void LoadDll(string libFileName)
        {
            var absoluteLibPath = Path.GetFullPath(libFileName);

            if (File.Exists(Environment.CurrentDirectory + "\\" + Path.GetFileName(libFileName)) == false)
                File.Copy(absoluteLibPath, Environment.CurrentDirectory + "\\" + Path.GetFileName(libFileName));

            Assembly.LoadFile(absoluteLibPath);
        }

        private static void CreateREngine()
        {
            var e = REngine.CreateInstance("test");
        }

    }

Has anybody seen this issue in the past? Any help would be appreciated.
Thanks,
Vitaly