Result type aa{sv} (array of maps string - variant) doesn't work

[smaug]

Hello,
I've been developing some code to communicate with Amarok 2, which provides some informations (about collection, interface org.kde.amarok.Collection) as an array of maps. Unforunately, ndesk-dbus throws an exception:

Unhandled Exception: System.Exception: Read non-zero byte at position 4 while expecting padding
  at NDesk.DBus.MessageReader.ReadPad (Int32 alignment) [0x00000]
  at NDesk.DBus.MessageReader.ReadArray (System.Type elemType) [0x00000]
  at NDesk.DBus.MessageReader.ReadValue (System.Type type) [0x00000]
  at NDesk.DBus.MessageHelper.GetDynamicValues (NDesk.DBus.Message msg, System.Type[] types) [0x00000]
  at NDesk.DBus.BusObject.SendMethodCall (System.String iface, System.String member, System.String inSigStr, NDesk.DBus.MessageWriter writer, System.Type retType, System.Exception& exception) [0x00000]
  at Amarok.ICollectionProxy.MprisQuery (System.String ) [0x00000]
  at Amarok.Amarok.Main () [0x00020] in /home/smaug/progs/gnome-do-amarok/gnome-do-amarok/Amarok.cs:27

I've tested version from git, but it also (before I was using 0.6.0 from Debian) doesn't work. Below is the code, which generates exception. The signature of MprisQuery method has been copied from dbus-explorer.

#v+

using System;
using System.Runtime.InteropServices;
using NDesk.DBus;
using System.Collections.Generic;

namespace Amarok
{

 [NDesk.DBus.Interface("org.kde.amarok.Collection")]
 interface ICollection
 {
  [return: Argument("result")]
  Dictionary<string, object>[] MprisQuery(string queryXml);
 };

 public class Amarok
 {
  public static int Main()
  {
   String q="<query version=\"1.0\"><limit value=\"5\" /><filters><or><include field=\"title\" value=\"Tonight, Tonight, Tonight\"/></or></filters><includeCollection id=\"localCollection\" /></query>";
   ICollection c = Bus.Session.GetObject<ICollection>("org.mpris.amarok",new ObjectPath("/Collection"));
   System.Console.WriteLine("{0}", c.MprisQuery(q).ToString());
   return 0;
  }

 }
}
#v-