>António,
>I've change de Content-type to multiplie options, but without any success. The error change from 415 to 500.
>The documentation of this webservice is lack...
>
>Any adicional tip?

Cesar, if these are HTTP errors, 500 means the message went through but the server couldn't handle it, in a very nasty way. Anyway, you can settle for the content-type that stopped raising the 415 error. The 500 is coming from somewhere else.

Is that a IIS server? Could you check on the Event Viewer for a more detailed description of what occurred?