WSE910 and WSE2005 errors

[Joël]

I'm trying to communicate with a webservice using kerberos authentication
(WSE3). Servers are under Windows 2003. Unfortunatly I allways get this error:

Message:
"WSE910: An error happened during the processing of a response message, and
you can find the error in the inner exception. You can also find the
response message in the Response property."

Response fault:
"System.Web.Services.Protocols.SoapException: Server did not recognize the
value of HTTP Header SOAPAction:
http://schemas.xmlsoap.org/ws/2005/02/trust/RST/SCT.
at System.Web.Services.Protocols.Soap11ServerProtocolHelper.RouteRequest()
at
System.Web.Services.Protocols.SoapServerProtocol.RouteRequest(SoapServerMessage message)
at Microsoft.Web.Services3.WseProtocol.RouteRequest(SoapServerMessage
message)
at System.Web.Services.Protocols.SoapServerProtocol.Initialize()
at System.Web.Services.Protocols.ServerProtocolFactory.Create(Type type,
HttpContext context, HttpRequest request, HttpResponse response, Boolean&
abortProcessing)"

InnerException messqge:
"WSE2005: Protection requirements in KerberosAssertion are not satisfied."


Does anyone know what could be the cause of this error, and how to solve it ?
Thanks for any help.

Joel