System.ArgumentNullException: Argument cannot be null.
Parameter name: value
  at MonoTouch.Foundation.NSMutableUrlRequest.set_BodyStream (MonoTouch.Foundation.NSInputStream value) [0x00006] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSMutableUrlRequest.g.cs:339
  at InputStreamTest.NativeUploader.Dispose (Boolean disposing) [0x00028] in /Users/nichal/Desktop/MfA 4.2.3RC1 + MD 3.0.3RC1 + MT 5.3.4RC/xamarin-monotouch-samples-40e2e8b/CustomInputStream/NativeUploader.cs:23
  at MonoTouch.Foundation.NSObject.Finalize () [0x00000] in /Developer/MonoTouch/Source/monotouch/src/Foundation/NSObject.cs:66