Why am I getting a SecurityFaultException

Hi,

i try the sample in the "Quick Start" of the SOAP api DSS, "GetVersion" méthode work but when I try another one like "ValidateInstruments" I got the FaultException with "A security erro has occured." message.

code below:

var identifier = new InstrumentIdentifier

{

IdentifierValue = "TRI.N",
IdentifierType = "RIC"

};

var validateInstrumentsRequest = new ValidateInstrumentsRequest

{

CredentialsHeader = _credentials,

request = new InstrumentValidationRequest

{

Identifiers = new[] { identifier }

}

};

var validateInstrumentsResponse = client.ValidateInstruments(validateInstrumentsRequest);
_credentials = validateInstrumentsResponse.CredentialsHeader;

any ideas ?

Laurent.