Hi Mikael,
Did you deploy the destination to the cloud portal landscape as described in the following link?
https://help.hana.ondemand.com/cloud_portal/frameset.htm?ad0dc4f760f447028efb8145de9d403c.html
In general, please review "Appendix B: Connecting Cloud Portal to an SAP Back-End System" for details about cloud portal connectivity to backends.
https://help.hana.ondemand.com/cloud_portal/frameset.htm?87deb781d6164e49bd9a04d5b5a7c53e.html
Regards,
Eliel.
Cloud portal Dev team.