Hi, Sandra.
Please use command like "tail -F /opt/idp/logs/idp-process.log" to start monitoring Shibboleth's log, then try the workflow you are having problems with again. You should be able to see SAML requests and responses in cleartext in this log, together with some error messages which may provide some hints on why it's not working.
Though it seems strange to me you are using url with ip address in it, instead of hostname. You should use the latter format whenever it's possible
Regards,
Alex