NAV 2015 Access to Nodes in request to Web Service by DLL

Hi,
I have problem resolving the nodes in the response after a request to Web Service using a DLL generated from Web Reference:
We need to request to a Web Service the Tracking No. of our expeditions using a DLL i created to do it.

Here is the code of the C/AL function:

HttpRequest := HttpRequest.TrackingService;
HttpDocu := HttpDocu.InfoSeguimiento;
HttpDocu := HttpRequest.GetEnvios(*****,*****,3082,TRUE,'1',FORMAT(Referencia),'','','','0',*****,*****);
MESSAGE(HttpDocu.MensajeSeguimiento);

HttpDocuAbonado := HttpDocu.Seguimiento;

HttpDocuSeguimiento := HttpDocuAbonado.SeguimientoAbonado;

MESSAGE(FORMAT(HttpDocuSeguimiento.EstadoDescripcion));

Where the HttpRequest Variable is the class who contain the metod GetEnvios(), and Tracking Service is the constructor.
With this code, i get response and i can show it with message function.

I also can assign the data in Method "Seguimiento" to variable HttpDocuAbonado.

But, when i try to assign HttpDocuAbonado.SeguimientoAbonado to HttpDocuSeguimiento, i have the error:


The variable "HttpDocuSeguimiento" is of type MRWTracking.MRWTracking.Seguimiento like specificated in the class:


Sorry about my bad english and thanks in advance.

Regards.