Troubleshooting Your SSO Configuration
If you do have a problem with SSO between Domino and WebSphere, check the following:
Ensure that the Web SSO Configuration document in the Domino Directory has been replicated to all servers participating in the SSO relationship. You should also do this if you have modified this document.
Ensure that you are using the same LDAP directory for both Domino and WebSphere and that the directory is accessible from all servers in your SSO domain. The LDAP utility ldapsearch provided by Domino comes in handy here.
Ensure that fully qualified host addresses are used in URLs when accessing the protected resources from a browser. The LTPA cookies are only generated for requests that specify a fully qualified host address. ...