Problem about soapRPC on HTTPS (IS 4.6)

Hi,
I’m using WebMethods Integration Server version 4.6 SP3 on jdk 1.3.1.

I have created a Web Service Connector from the WSDL File in order to call an external partner webservice.

According with the content of the WSDL file, the Web Service Connector performs a soapRPC call on https.

Our partner gave us the private key and certificate to use for the https connection.
So, I have modified the Web Service Connector putting the call to the WebMethods service
pub.security:setKeyAndChain (in order to force the use of the our partner certificates) before the call
to the soapRPC service and putting the call to the WebMethods service pub.security:clearAndChain (in order to revert back
to the default certificate) after the call to the soapRPCservice.

When I invoke the Web Service Connector, I get the error:
iaik.security.ssl.SSLException: Peer sent alert: Alert Fatal: handshake failure,
that it is raised by soapRPC internal service.

Any ideas or suggetions to better debug the SSL handshaking (e.g. to enable SSL handshake debugging in IS) ?

TIA.
Marco