Using Domino CA authority to generate SSL certificate don't work : error sec_error_bad_signature on browser

Hi, we use the Domino CA authority to generate a SSL certificate for web client using this quick guide : http://www-01.ibm.com/support/docview.wss?uid=swg21114148. We have no error when generate the certificate but we cannot access to the web server in HTTPS mode. Firefox said the certificate is incorrect: sec_error_bad_signature. I have the same error on two Domino server.