Horizon and Spring Security app

I am wondering if anybody have successfully integrated Horizon with the custom Spring Security application? I am looking at that one:http://static.springsource.org/spring-security/site/extensions/saml/index.html and can't figure the details. When I import metadata in Horizon I get the error: "Requested action 'getSPAttrs' failed."

How do I debug these types of issues? I guess poeple shlould be able to add applications outside of the list by just manually entering appropriate fields.

Thanks

Vladimir