ObjectAttach transaction results in Exception "System.MissingMethodException"

Hello,

I am trying to run API method AttachObject. It is resulting in the following exception :

Method not found: 'Infra.Rules.WebUploadResult Infra.Rules.Objects.ObjectInsert(Infra.Rules.InfraSession, Byte[] ByRef, Int32 ByRef, System.String ByRef, System.String ByRef, Int32 ByRef, Int32 ByRef, Int32 ByRef, Boolean ByRef, System.String ByRef, System.String ByRef, System.String ByRef, System.String ByRef, System.String ByRef, Infra.Utils.IFieldCollection)'.

   at Infra.API.ServiceImplementation.ServiceManager.ObjectAttach(ObjectRequest request)

   at SyncInvokeObjectAttach(Object , Object[] , Object[] )

   at System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke(Object instance, Object[] inputs, Object[]& outputs)

   at System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage41(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage2(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1(MessageRpc& rpc)

   at System.ServiceModel.Dispatcher.MessageRpc.Process(Boolean isOperationContextSet)

System.MissingMethodException

"

Here is the code we use to prepare and call ObjectAttach Transaction:

///////////

var oar = new ObjectRequest();

oar.eEntityType = EntityType.Call;

                //oar.sFileName = "testerFile";

                byte[] bytes = System.IO.File.ReadAllBytes("C:\\Temp\\bb.png");

                oar.xContent = bytes;

                oar.nContentSize = bytes.Length;

                oar.sObjectAbstract = "Testing ObjectAttach Subject";

                oar.sObjectTitle = "Testing ObjectAttach Title";

                oar.lEntityRef = "~" + 12033;// call_number;

                var result = apiService.ObjectAttach(oar);

///////////////

Any input would be greatly appreciated.

Thanks a lot,

Alex Nebogatov