delete incident attachments with SOAP Api

Content

Hello 

I would like to delete incident file attachment through SOAP Api.

I tried this code, but I receive the error "The content type text/html; charset=UTF-8 of the response message does not match the content type of the binding (text/xml; charset=utf-8). If using a custom encoder, be sure that the IsContentTypeSupported method is implemented properly."

public void deleteIncidentAttachments(long incidentID, FileAttachmentIncident[] fattachs)
{
Incident incident = new Incident();
incident.ID = new ID(); ;
incident.ID.id = incidentID;  // input
incident.ID.idSpecified = true;
 
incident.FileAttachments = fattachs;  // input, retrieved before
foreach (FileAttachmentIncident x in incident.FileAttachments)
{
   x.action = SOAP.ActionEnum