server does not expose service

When I enable server reflection in C# server like this

var reflectionServiceImpl = new ReflectionServiceImpl(Greeter.Descriptor, ServerReflection.Descriptor);
server = new Server()
{
    Services =
    {
        // the server will serve 2 services, the Greeter and the ServerReflection
        ServerReflection.BindService(new GreeterImpl()),
        ServerReflection.BindService(reflectionServiceImpl)
    },
    Ports = { { "localhost", 50051, ServerCredentials.Insecure } }
};
server.Start();

I get this error

"Error":"target server does not expose service